Method for cleaning plasma processing apparatus

Abstract

To efficiently clean a chamber in order to maximize productive time while maintaining film quality, substrate to substrate and within substrate uniformity, speed and a defective rate within acceptable limits.SOLUTION: A method includes the steps of: introducing a first cleaning gas mixture into a chamber via a first gas inlet, in which the first cleaning gas mixture contains a first oxygen-containing component; generating a first plasma in the chamber from the first cleaning gas mixture; introducing a second cleaning gas mixture into a remote plasma source, in which the second cleaning gas mixture contains a fluorine-containing component; generating a second plasma in the remote plasma source from the second cleaning gas mixture, in which the second plasma contains fluorine radicals; and performing a second cleaning step by allowing fluorine radicals from the second plasma to enter the chamber and introducing a third cleaning gas mixture into the chamber at the same time as the fluorine radicals from the second plasma, in which the third cleaning gas mixture contains a second oxygen-containing component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for cleaning a chamber of a plasma processing apparatus.The present invention also relates to a plasma processing apparatus. [Background technology]

[0002] The fabrication of devices, such as semiconductor devices, frequently involves the deposition of films, e.g., dielectric films including silicon oxide, SiN, SiC, SiOC, and SiCN. In many back-end processing (BEOL) and packaging applications, these films must also be deposited at relatively low temperatures, below 450° C., to prevent damage or distortion of components, which can impact the deposition techniques available to deposit these films in a cost-effective manner. The most widely used technique for depositing low-temperature films is plasma-enhanced chemical vapor deposition (PECVD), which utilizes a plasma to decompose a precursor in a chamber that contains the substrate for deposition. This technique can produce excellent low-temperature film properties at relatively high deposition rates. However, deposition is not limited to the substrate surface because the plasma extends beyond the substrate surface. This results in a buildup of deposits in the chamber over time. This deposit requires removal and surface treatment of the interior of the chamber, as it can be a source of particles that contaminate future deposition processes. Ideally, the interior surfaces of a PECVD process chamber are cleaned and possibly coated without breaking vacuum to maintain productive operation of the system. The frequency of these cleaning cycles will vary depending on the thickness of the deposit and the process conditions, such as deposition temperature, plasma power, and precursors used to form the required film.

[0003] In a capacitively coupled parallel plate PECVD system, the deposition plasma is generated by flowing process gases into the chamber at reduced pressure and applying an RF potential between a "showerhead" or gas distribution plate and the substrate support on which the substrate is placed. After a deposition cycle, when the substrate is removed from the system, a cleaning gas may be introduced into the chamber through the showerhead and then an RF potential may be applied to clean the interior surfaces of the chamber. This chamber cleaning step may be performed after each substrate or series of substrates, where the frequency of the cleaning step is determined by the effectiveness of the cleaning step to control particle generation. Then, if necessary, a "stick-on" deposition step may be performed to coat the surfaces of the chamber. This step helps to cover residual components remaining in the chamber from the cleaning step and provide a consistent surface coating. Although this process gas change sequence is easy to achieve in practice, the cleaning process is limited, mainly due to the relatively high ratio of free ions to free radicals in the RF plasma. Ionic components tend to roughen the chamber components over time, and ion density varies significantly throughout the chamber, so some areas of the chamber take a long time to clean while other areas are overexposed. Remote plasma sources located outside the chamber, which produce high radical concentrations at relatively low ion densities, can be used to address these concerns, but these sources add complexity and cost to the system, and their performance depends on the composition of the deposits that build up on the chamber components.

[0004] PECVD productivity is determined by the number of substrates processed in a given period of time. Production time is wasted when the system is not depositing a film on a substrate during a cleaning step or during a pre-deposition step when no substrates are present in the chamber. In a production environment, it is important to maximize the time spent depositing a film on a substrate while maintaining a stable process within acceptable defect limits.

[0005] PECVD deposited dielectrics such as silicon oxide, SiN, and SiOC are formed by the fluorine radicals F from dissociated NF3. * The reaction mechanism for etching SiO2 using NF3 remote plasma can be seen in the following (1) and (2). (1) 2NF3(g) → N2(g) + 6F * (2) SiO2(s)+4F * →SiF4(g)+O2(g)

[0006] SiCN and SiC films with high C content, typically greater than 20 at. % C, have a high C content due to preferential removal of silicon, resulting in F * Radicals alone are not effectively removed, resulting in residual carbon-based by-products in the chamber even after extended cleaning.

[0007] Therefore, what is needed is a method to efficiently clean a PECVD chamber to maximize production time while maintaining acceptable film quality, inter- and intra-substrate uniformity, rate, and defectivity. By keeping cleaning time to a minimum, cleaning gas consumption can also be reduced, providing cost and environmental benefits. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2007 / 0207275 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention, in at least some of its embodiments, aims to address the problems, desires and needs set forth above. [Means for solving the problem]

[0010] According to a first aspect of the present invention, there is provided a method for cleaning a chamber of a plasma processing apparatus to remove deposits formed after using the plasma processing apparatus to deposit a dielectric material comprising silicon and carbon, the method comprising: In a first introducing step, a first cleaning gas mixture is introduced into the chamber through a first gas inlet, the first cleaning gas mixture including a first oxygen-containing component; generating a first plasma in the chamber from a first cleaning gas mixture in a first cleaning step; In a second introducing step, introducing a second cleaning gas mixture into the remote plasma source, the second cleaning gas mixture including a fluorine-containing component; generating a second plasma from the second cleaning gas mixture in a remote plasma source, the second plasma including fluorine radicals in a remote plasma generating step; performing a second cleaning step by admitting fluorine radicals from a second plasma into the chamber and introducing a third cleaning gas mixture into the chamber simultaneously with the fluorine radicals from the second plasma, the third cleaning gas mixture including a second oxygen-containing component; Includes.

[0011] Without wishing to be bound by theory or speculation, it is believed that the first plasma generated within the chamber provides ion bombardment to rapidly oxidize the deposits, producing altered deposits. However, this first plasma does not remove the deposits, and therefore ion damage to the chamber surfaces and internal components is minimized. The subsequent introduction of fluorine radicals generated by the second plasma of the remote plasma source and a second oxygen-containing component into the chamber increases the residence time of the fluorine radicals, allowing for more effective removal of the altered deposits, while simultaneously activating the second oxygen-containing component to further oxidize the deposits.

[0012] For the avoidance of doubt, the term "radical" is intended to refer to an uncharged reactive species having one or more unpaired electrons. Radicals may be atomic or molecular. It is expected that substantially all (95% or more) of the electrons and ions generated in the remote plasma source will not reach the chamber.

[0013] The third cleaning gas mixture may be introduced into the chamber separately from the fluorine radicals from the second plasma. The third cleaning gas mixture may be introduced into the chamber through the first gas inlet. The fluorine radicals may be introduced into the chamber through a connector connecting the chamber and a remote plasma source. The chamber may include a gas inlet system, which serves as a conduit for the radicals generated in the remote plasma source and the first and second cleaning gas mixtures. The gas inlet system may include a showerhead. As known to those skilled in the art, a showerhead is a gas delivery element having a plurality of perforations or other openings. The perforations or other openings allow the gas to be introduced uniformly into the chamber. Generally, the showerhead includes a first plate having at least one gas inlet and a second plate having perforations or other openings. The first and second plates are spaced apart to define a cavity. The gas inlet system may include a first gas inlet. The gas inlet system may include a second gas inlet.

[0014] The dielectric material may include silicon carbonitride or silicon carbide. The dielectric material may include hydrogenated silicon carbonitride (SiCN:H). The dielectric material may include amorphous carbon. The dielectric material may include at least 20 atomic % carbon. The dielectric material may include at least 30 atomic % carbon.

[0015] The plasma processing apparatus may be a PECVD apparatus. The remote plasma source may be an inductively coupled plasma (ICP) source or any other suitable plasma source. The plasma generating means may be a radio frequency (RF) driven capacitively coupled parallel plate system. The plasma processing apparatus may include a substrate support located within the chamber. The method may be performed after plasma processing of one or more substrates. The one or more substrates may include one or more semiconductor substrates. The one or more semiconductor substrates may include one or more silicon substrates. The one or more semiconductor substrates may include one or more semiconductor wafers, for example one or more silicon wafers. The method may be performed after an isolation or passivation plasma processing step. The method may be performed after a TSV, via exposure, or interposer fabrication plasma processing step.

[0016] The first oxygen-containing component may be selected from O2, N2O, and O3. The first oxygen-containing component may be O2. The second oxygen-containing component may be selected from O2, N2O, and O3. The second oxygen-containing component may be O2. The fluorine-containing component may be NF3. The first cleaning gas mixture may include at least one inert gas component. The at least one inert gas component of the first cleaning gas mixture may include Ar and / or He. The second cleaning gas mixture may include at least one inert gas component. The inert gas component of the second cleaning gas mixture may include Ar and / or He. At least one inert gas component, such as Ar or He, may be added to the cleaning gas mixture used to generate the first plasma and / or the second plasma to aid in initiating the plasma and to stabilize the generated plasma.

[0017] The ratio of the flow rate in sccm of the fluorine-containing component to the flow rate in sccm of the second oxygen-containing component can be about 4:1 to about 2:3. The ratio of the flow rate in sccm of the fluorine-containing component to the flow rate in sccm of the second oxygen-containing component can be about 3:2. The flow rate of the first oxygen-containing component can be about 200 sccm to about 2000 sccm. The flow rate of the first oxygen-containing component can be about 1000 sccm. The flow rate of the fluorine-containing component can be about 1000 sccm to about 5000 sccm. The flow rate of the fluorine-containing component can be about 3000 sccm. The flow rate of the second oxygen-containing component can be about 1000 sccm to about 5000 sccm. The flow rate of the second oxygen-containing component can be about 2000 sccm.

[0018] The chamber may be maintained under vacuum by a vacuum means such as a vacuum pump. During the first introduction step and / or the first cleaning step, the chamber may be maintained at a pressure of about 500 mTorr (66700 Pa) to about 5000 mTorr (667000 Pa). During the first introduction step and / or the first cleaning step, the chamber may be maintained at a pressure of about 1000 mTorr (133000 Pa). During the second cleaning step, the chamber may be maintained at a pressure of about 500 mTorr (66700 Pa) to about 5000 mTorr (667000 Pa). During the second cleaning step, the chamber may be maintained at a pressure of about 2500 mTorr (333000 Pa).

[0019] During the first cleaning step, a plasma may be maintained in the chamber using high frequency RF power. During the first cleaning step, a plasma may be maintained in the chamber using high frequency RF power and low frequency RF power. The high frequency RF power may have a frequency between 10 MHz and 20 MHz. The low frequency RF power may have a frequency between 375 kHz and 2 MHz. The high frequency RF power may provide a power between about 500 W and about 1500 W during the first cleaning step. The high frequency RF power may provide a power of about 1000 W during the first cleaning step.

[0020] The first cleaning step may have a duration of about 20 seconds to about 60 seconds. The first cleaning step may have a duration of about 30 seconds.

[0021] The second cleaning step may include monitoring a composition of an environment within the chamber and determining an endpoint of the second cleaning step based on the composition of the environment within the chamber. The monitoring of the composition of the environment within the chamber may be performed by an infrared gas analyzer.

[0022] No plasma may be generated in the chamber during the second cleaning step.

[0023] The method may further include performing a pre-deposition chamber treatment after the second cleaning step.

[0024] According to a second aspect of the present invention, there is provided a plasma processing apparatus, comprising: A chamber; a plasma generating means configured, in use, to generate a plasma within the chamber; at least one gas inlet; a remote plasma source configured to generate a plasma during use; a connector for connecting the remote plasma source to the chamber, the connector being configured, during use, to allow radicals from a plasma generated in the remote plasma source to enter the chamber while simultaneously preventing a majority of ions generated in the remote plasma source from entering the chamber; A controller, Here, the controller is in use: introducing a first cleaning gas mixture into the chamber through a first gas inlet of the at least one gas inlet, the first cleaning gas mixture comprising a first oxygen-containing component; generating a first plasma in the chamber from the first cleaning gas mixture using a plasma generating means; A second cleaning gas mixture is introduced into the remote plasma source, the second cleaning gas mixture comprising a fluorine-containing component; a second plasma is generated in the remote plasma source from the second cleaning gas mixture, the second plasma comprising fluorine radicals; and The fluorine radicals from the second plasma are allowed to enter the chamber through the connector, and a third cleaning gas mixture is introduced into the chamber simultaneously with the fluorine radicals from the second plasma, the third cleaning gas mixture including a second oxygen-containing component.

[0025] The plasma processing apparatus may be a PECVD apparatus. The remote plasma source may be an inductively coupled plasma (ICP) source or any other suitable plasma source. The plasma generating means may be a radio frequency (RF) driven capacitively coupled parallel plate system.

[0026] The controller may be configured, during use, to introduce the third cleaning gas mixture into the chamber through the at least one gas inlet. The plasma processing apparatus may include a monitoring device configured to monitor, during use, a composition of an environment within the chamber, and the controller is configured, during use, to determine an endpoint of the second cleaning step based on the composition of the environment within the chamber monitored by the monitoring device. The monitoring device may include an infrared gas analyzer.

[0027] The connector may be electrically insulating. The connector may be formed of a dielectric material, such as ceramic. The connector may include a plurality of gas introduction holes. Each of the gas introduction holes may have a diameter of less than 10 mm, preferably less than 5 mm. In this manner, plasma generated in the remote plasma source is substantially prevented from reaching the chamber. The connector may include a plug having a plurality of gas introduction holes formed therethrough.

[0028] The chamber may include a gas inlet system, which serves as a conduit for radicals generated in the remote plasma source. The gas inlet system may include a showerhead. The gas inlet system may include a first gas inlet. The gas inlet system may include a second gas inlet. The gas inlet system may include additional gas inlets, e.g., a third gas inlet. The plasma processing apparatus may include a substrate support disposed within the chamber.

[0029] For the avoidance of doubt, whenever reference is made herein to "comprising" or "including" and similar terms, it is understood that the invention also includes more restrictive terms such as "consisting of" and "consisting essentially of". Although the invention has been described above, the invention extends to any inventive combination of the features set out above or in the following description, drawings or claims. For example, any feature disclosed in relation to the first aspect of the invention may be combined with any feature of the second aspect of the invention, and vice versa. [Brief description of the drawings]

[0030] Aspects of methods and apparatus according to the present invention will now be described with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of a plasma processing apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a graph showing the relative intensity of volatile components in a chamber versus duration of a comparative cleaning step. [Diagram 3] 1 is a graph showing the relative intensity of volatile components in a chamber versus duration of a comparative cleaning step. [Figure 4] 1 is a graph showing the relative intensity of volatile components in a chamber versus duration of a comparative cleaning step. [Diagram 5] 1 is a graph showing the relative intensity of volatile components in a chamber versus duration of a comparative cleaning step. [Figure 6]2 is a flow chart illustrating a method according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] FIG. 1 shows a schematic diagram of a PECVD system 1 according to one embodiment of the present invention. Within the chamber 2, a process region 3 where plasma is generated is defined between a substrate support 5 and a gas introduction system including a showerhead 4. Gases enter the back of the showerhead 4 and are injected into the process region 3 through a series of small holes 10 isolated in the showerhead 4 by an internal gas distribution plate 11. The substrate support 5 is grounded and the showerhead 4 is powered by a plasma generating means, which includes two different RF power supplies 14, 15, each operating at a different RF frequency, and their associated matching units 16, 17. There is a dielectric breakdown (not shown) between the aluminum showerhead 4 and the metal chamber 2. Alternative plasma generating means may also be used, such as one where the substrate support 5 is RF powered and the gas distribution plate 11 is grounded. Process and cleaning gases enter the gas inlet system through pipes 6, 7, which contain isolation valves 8, 9. Multiple gas sources are connected to the pipes 6, 7 by a manifold (not shown) with isolation valves, mass flow controllers, and related components. The chamber 2 is evacuated through line 12 by a pump (not shown).

[0032] A typical process cycle begins by loading a substrate into the evacuated chamber 2 and placing the substrate on the substrate support 5. An annular uniformity ring 13 is placed close to the edge of the substrate on the substrate support surface. The process gas or gas mixture enters the system through gas pipe 6 with valve 8 open and enters chamber 2 through showerhead 4. Once the desired gas flow rate and pressure are achieved by the system controller, RF power is supplied to the showerhead 4 by either or both of RF sources 14, 15 to strike a plasma in chamber 2 between the showerhead 4 and the substrate support 5. The high frequency RF source 14 typically operates at 10-20 MHz, while the low frequency RF source 15 typically operates at 375 kHz-2 MHz. Matching units 16 and 17 allow efficient coupling of the RF to the showerhead 4. Once the desired thickness of deposition is achieved, the power is turned off and the flow of process gas is stopped. Chamber 2 is depressurized and the substrate is then removed from the chamber.

[0033] In a typical remote chamber cleaning process, reactive cleaning gases and any inert gases pass through the gas pipe 7, the connector 20, the remote plasma source 18 and the valve 9, and enter the chamber 2 through the showerhead 4. Then, power is supplied from the power supply 19 to the remote source 18 to generate a high-density plasma in the remote source 18, which provides a source of radicals to clean the chamber 2 through the connector 20. The connector 20 may be disposed at any position downstream of the remote source 18 before the showerhead 4. The connector 20 may be electrically insulating, such as a dielectric connector, and may be provided with multiple gas conducting holes with a diameter of less than 10 mm to ensure that energetic ions in the plasma generated in the remote plasma source 18 do not reach the chamber 2, but radicals can reach the chamber 2.

[0034] To determine the end point of the chamber cleaning, a monitoring device 21, in this case an infrared gas analyzer, is used in exhaust line 12. By monitoring characteristics, such as the IR signature, of the gases and volatile components exiting chamber 2 via exhaust line 12, it is possible to map the intensity of the emitted light as a function of time to determine when chamber 2 has been completely cleaned. System 1 further includes a controller 22 that is configured to control the components of system 1 in both normal operating and cleaning modes.

[0035] Experimental studies were carried out using a Delta™ fxP PECVD system manufactured by SPTS, Newport, UK. This is a capacitively coupled mixed frequency parallel plate single wafer PECVD system. Using 300 mm silicon wafers with a standard thickness of approximately 775 μm, silicon carbonitride films ranging from 150 nm to 500 nm in thickness were deposited on bare silicon wafers and cleaning parameters were varied to determine the optimum cleaning process chemistry and physics. However, alternative plasma processing systems, substrate materials, substrate sizes, and dielectric films containing silicon and carbon may be used. An MKS Astron™ reactive gas generator was used as the remote source. Other types of plasma generators may be contemplated instead. All cleaning cycles used the same deposition thickness and silicon carbonitride film. The endpoint times included a fixed overetch period to support long term chamber performance. Silicon carbonitride films deposited by PECVD under standard BEOL conditions at temperatures below 450° C. contained significant hydrogen content and are thereby more accurately defined as SiCN:H films. However, for the sake of brevity, such films and deposits will be referred to as SiCN.

[0036] In a first comparative example, a remote plasma NF3 clean was performed following the SiCN deposition. The endpoint tracking results of the gas composition and volatile compound monitoring are shown in FIG. 2, where the X-axis shows the cleaning time and the Y-axis shows the relative intensity of the volatile compounds in the exhaust line. After about 25 seconds, the emission peaks, then drops rapidly at about 50 seconds, and slowly drops until the remote plasma is extinguished. After about 300 seconds, volatile products are still detected in the exhaust line, indicating that the endpoint has not been reached and the chamber is not completely clean. It was found that an additional 200 seconds of remote plasma generation was required to finish cleaning the chamber and reach the endpoint. For comparison, a comparable thickness SiO2 deposition takes less than 80 seconds to reach the cleaning endpoint under similar process conditions.

[0037] Next, in the second comparative example, the cleaning method is modified to include a capacitive RF oxygen plasma in the PECVD chamber for 60 seconds at a chamber pressure of 1000 mTorr, followed by cleaning of the remote plasma source. In the first introduction step, a 1000 sccm O2 flow is introduced into the PECVD chamber through the showerhead, and 1000 W of high frequency RF power is coupled into the PECVD chamber through the showerhead to ignite the O2 to form a first oxygen-containing plasma in the first cleaning step. During the first cleaning step, there is no significant CO or CO2 IR absorption as monitored by an infrared gas analyzer. Without wishing to be bound by theory or speculation, it is believed that rather than removing the SiCN deposits, the carbon content in the SiCN deposits is oxidized by the oxygen-containing plasma to form SiCON altered deposits. These altered SiCON deposits can then be more effectively etched in a subsequent remote plasma clean.

[0038] Figure 3 shows the effect of an initial RF oxygen plasma prior to the NF3 remote plasma cleaning step compared to the comparative example shown in Figure 2. A significant increase in integrated emission intensity can be seen when compared to an equivalent amount of deposition cleaned with NF3 remote plasma alone. This suggests that although both methods reach the cleaning endpoint at approximately the same time as measured by an IR detector, residual non-volatile material is more likely to be present in the chamber after the method that includes an initial oxygen-containing plasma clean.

[0039] It has been found that a stable RF oxygen plasma can be maintained in the chamber using pressures between 500 mTorr and 5000 mTorr, gas flow rates between 200 sccm and 2000 sccm, and RF powers between 500 W and 1500 W, which can provide a wide process window for the first cleaning step.

[0040] Next, in the third comparative example, modification of the remote cleaning chemistry of the second cleaning step was investigated by maintaining the pressure in the chamber at 2500mT with a total flow rate of 5000sccm of reactive gases and varying the NF3 flow rate through the remote plasma source to establish optimized process conditions. Each test was performed using an oxygen-based plasma in the chamber without a first cleaning step. For cleaning SiCN deposits, the optimal ratio was determined to be a reduced NF3 flow rate of 3000sccm and an oxygen-containing component, in this case 2000sccm of O2 gas. However, this particular optimal ratio is expected to depend on the nature of the deposits being removed. Without wishing to be bound by any theory or speculation, it is believed that the addition of an oxygen-containing component to the remotely generated plasma activates the oxygen-containing component and allows for oxidation of the constituent carbon of the SiCN deposits. It was also found that mixing remotely ionized free fluorine radicals with the oxygen-containing component in the PECVD showerhead and chamber rather than in the remote source increases the residence time of the fluorine radicals, allowing for more effective etching of the altered SiCON deposits. These effects combine to reduce the time to thoroughly clean the chamber of deposits, as shown in FIG. 4 and summarized in Table 1.

[0041] [Table 1]

[0042] The first cleaning step including an oxygen-containing plasma was then combined with a subsequent modified remote plasma cleaning step to further reduce the time it takes to complete the cleaning of the chamber. It was determined that the combination of a first cleaning step including the generation of a first plasma in the chamber including an oxygen-containing component and a second cleaning step including the generation of a plasma from a fluorine-containing component in a remote source and then cleaning the chamber with fluorine radicals and an oxygen-containing component would reduce the cleaning time of the chamber as well as prevent residues from building up in the PECVD chamber and potentially hindering the long-term performance of the chamber through particle generation. This is evidenced by tracking the amount of residue build-up seen after deposition and during cleaning chamber inspection. In the absence of a first plasma clean, a yellow / orange coating was observed to gradually grow on the interior surfaces, e.g., the chamber lining and showerhead, over multiple depositions. However, this coating was not observed when the first and second cleaning steps of the present invention were combined for cleaning.

[0043] Figure 5 shows a comparison between standard remote plasma cleaning, modified remote plasma cleaning, and a combination of a first cleaning step and a second cleaning step according to the present invention. In Figure 5, it can be seen that the combination of a first cleaning step followed by a second cleaning step increases the peak intensity of the Si-F IR gas analyzer signal and the etch rate compared to the modified remote cleaning alone. Table 2 shows the best cleaning times achieved with the individual cleaning modifications and combinations of cleaning modifications.

[0044] [Table 2]

[0045] A method for cleaning the chamber of a plasma processing apparatus, in this case a PECVD apparatus, to remove deposits formed after the plasma processing apparatus is used to deposit a dielectric material containing silicon and carbon, according to an exemplary embodiment of the present invention, is summarized in FIG. 6. In a first introduction step 101, the substrate is removed from the PECVD chamber, previous gaseous or volatile components are evacuated from the chamber, and a first cleaning gas mixture containing a first oxygen-containing component is introduced into the chamber. In one embodiment, the first cleaning gas mixture contains or consists of O2 gas and is introduced into the chamber to achieve a partial pressure of about 1000 mT. In a first cleaning step 102, a first plasma is generated in the chamber between the showerhead and the wafer support by applying RF power for about 30 seconds to oxidize the carbon content of the deposit. The exact duration of the first cleaning step depends on the thickness and carbon content of the deposit. The RF plasma is then extinguished. In a second introduction step 103, a second cleaning gas mixture containing a fluorine-containing component, in this case NF3, is injected into the remote plasma source. In the remote plasma generation step 104, the fluorine-containing components are dissociated when power is applied to the remote plasma source to generate fluorine radicals. In the second cleaning step 105, fluorine radicals and a third cleaning gas mixture containing a second oxygen-containing component, in this case O2 gas, are sent to the showerhead and introduced into the chamber to clean the altered deposits. Preferably, no plasma is generated in the chamber during the second cleaning step to prevent ions from damaging the exposed surfaces and internal components of the chamber as the deposits are removed. The duration of the second cleaning step depends on the composition and thickness of the deposits and can be run for a set time or, if monitored to an endpoint, the second cleaning step is terminated upon determining the endpoint and the end of the cleaning process. At the endpoint, all gases are evacuated from the chamber and, if necessary, the chamber is purged before the pre-deposition chamber processing step. At this point, the chamber is ready for the next substrate processing.

[0046] Without being bound to any particular theory or speculation, it is believed that the first plasma in the chamber oxidizes the carbon content of the deposits, producing altered deposits, as indicated by the absence of IR absorption of CO and CO2 in the exhaust line. The first plasma provides ion bombardment to rapidly oxidize the deposits. However, this high energy plasma does not remove the deposits itself, thus avoiding ion damage to the chamber surfaces. In the second introduction step and the second cleaning step, by not mixing the fluorine-containing and oxygen-containing components in the remote source, the fluorine radical density in the chamber, and therefore the etch rate of the deposits, is increased due to reduced recombination, and O2 is dissociated upon reaching the showerhead, promoting further alteration of the deposits.

Claims

1. 1. A method for cleaning a chamber of a plasma processing apparatus to remove deposits formed after deposition of a silicon and carbon containing dielectric material using said plasma processing apparatus, comprising the steps of: In a first introducing step, a first cleaning gas mixture is introduced into the chamber through a first gas inlet, the first cleaning gas mixture including a first oxygen-containing component; generating a first plasma in the chamber from the first cleaning gas mixture in a first cleaning step; In a second introducing step, introducing a second cleaning gas mixture into the remote plasma source, the second cleaning gas mixture including a fluorine-containing component; generating a second plasma from a second cleaning gas mixture in the remote plasma source, the second plasma comprising fluorine radicals; performing a second cleaning step by admitting fluorine radicals from the second plasma into the chamber and introducing a third cleaning gas mixture into the chamber simultaneously with the fluorine radicals from the second plasma, the third cleaning gas mixture including a second oxygen-containing component; method.

2. 10. The method of claim 1, wherein the third cleaning gas mixture is introduced into the chamber separately from the fluorine radicals from the second plasma.

3. The method of claim 1 or 2, wherein the dielectric material comprises silicon carbonitride or silicon carbide.

4. The method of claim 1 , wherein the dielectric material comprises at least 20 atomic % carbon.

5. The first oxygen-containing component is O ２ The method according to any one of claims 1 to 4, wherein

6. The second oxygen-containing component is O ２ The method according to any one of claims 1 to 5, wherein

7. The fluorine-containing component is NF ３ The method according to any one of claims 1 to 6, wherein

8. 8. The method of claim 1, wherein the ratio of the flow rate in sccm of the fluorine-containing component to the flow rate in sccm of the second oxygen-containing component is from about 4:1 to about 2:

3.

9. 9. The method of claim 8, wherein the ratio of the flow rate in sccm of the fluorine-containing component to the flow rate in sccm of the second oxygen-containing component is about 3:

2.

10. The method of any one of claims 1 to 9, wherein the flow rate of the fluorine-containing component is between about 1000 sccm and about 5000 sccm.

11. The method of claim 10 , wherein the flow rate of the fluorine-containing component is about 3000 sccm.

12. The method of any one of claims 1 to 11, wherein the flow rate of the second oxygen-containing component is between about 1000 sccm and about 5000 sccm.

13. 13. The method of claim 12, wherein the flow rate of the second oxygen-containing component is about 2000 sccm.

14. 14. The method of any one of claims 1 to 13, wherein during the first introducing step, the chamber is maintained at a pressure of about 500 mTorr (66700 Pa) to about 5000 mTorr (667000 Pa).

15. 15. The method of any one of claims 1 to 14, wherein the chamber is maintained at a pressure of about 500 mTorr (66700 Pa) to about 5000 mTorr (667000 Pa) during the first cleaning step.

16. 16. The method of any one of claims 1 to 15, wherein the chamber is maintained at a pressure of about 500 mTorr (66700 Pa) to about 5000 mTorr (667000 Pa) during the second cleaning step.

17. 17. The method of claim 1, wherein during the first cleaning step, the plasma is maintained in the chamber using high frequency RF power.

18. The method of claim 16, wherein high frequency RF power provides a power of about 500 W to about 1500 W during the first cleaning step.

19. 19. The method of any one of claims 1 to 18, wherein the first cleaning step has a duration of about 20 seconds to about 60 seconds.

20. 20. The method of claim 1, wherein the second cleaning step includes monitoring a composition of an environment in the chamber and determining an endpoint of the second cleaning step based on the composition of the environment in the chamber.

21. 21. The method of any one of claims 1 to 20, wherein no plasma is generated in the chamber during the second cleaning step.

22. 22. The method of claim 1, further comprising performing a pre-deposition chamber treatment after the second cleaning step.

23. A plasma processing apparatus comprising: A chamber; plasma generating means arranged, in use, to generate a plasma within said chamber; at least one gas inlet; a remote plasma source configured to generate a plasma during use; a connector connecting the remote plasma source to the chamber, the connector being configured, in use, to allow radicals from a plasma generated in the remote plasma source to enter the chamber while simultaneously preventing a majority of ions generated in the remote plasma source from entering the chamber; A controller, wherein the controller, during use, introducing a first cleaning gas mixture into the chamber through a first gas inlet of the at least one gas inlet, the first cleaning gas mixture comprising a first oxygen-containing component; generating a first plasma in the chamber from the first cleaning gas mixture using the plasma generating means; introducing a second cleaning gas mixture into the remote plasma source, the second cleaning gas mixture comprising a fluorine-containing component; generating a second plasma in the remote plasma source from a second cleaning gas mixture, the second plasma comprising fluorine radicals; and fluorine radicals from the second plasma are admitted to the chamber through the connector, and a third cleaning gas mixture is introduced into the chamber simultaneously with the fluorine radicals from the second plasma, the third cleaning gas mixture including a second oxygen-containing component. Plasma processing equipment.

24. The plasma processing apparatus of claim 23, which is a PECVD apparatus.

25. 25. The plasma processing apparatus of claim 23 or 24, wherein the controller is configured, during use, to introduce the third cleaning gas mixture into the chamber through at least one gas inlet.

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