Densification of dielectric films using inductively coupled high density plasma

Abstract

The invention relates to densification of dielectric films using inductively coupled high density plasma. A method for densifying a dielectric film on a substrate includes disposing a substrate including a dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling a pressure in the substrate processing chamber to be greater than or equal to a predetermined pressure; a first power level is provided at a first frequency to a coil to generate a plasma in the substrate processing chamber. The coil is disposed around an outer surface of the substrate processing chamber. The method includes densifying the dielectric film for a predetermined time. The pressure and the first power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film.

Description

This application is a divisional application of the application with the application number 201710305801.2, the application date of May 3, 2017, and the invention title of "Densification of Dielectric Films Using Inductively Coupled High-Density Plasma". Technical Field

[0001] The present disclosure relates to a substrate processing system, and more particularly to densification of dielectric films using a high-density inductively coupled plasma source. Background Art

[0002] The background description provided here is for the purpose of generally presenting the background of the present disclosure. To the extent that the description in this background art section and aspects that are not otherwise considered prior art at the time of filing, the work of the presently named inventors is neither expressly nor implicitly admitted as prior art against the present disclosure.

[0003] A substrate processing system can be used to deposit and etch films on a substrate (such as a semiconductor wafer). A substrate processing system typically includes a processing chamber, a gas distribution device, and a substrate support. During processing, the substrate is disposed on the substrate support. Different gas mixtures can be introduced into the processing chamber, and radio frequency (RF) plasma can be used to activate chemical reactions.

[0004] Shallow trench isolation (STI) features provide electrical isolation between individual transistor devices in an integrated circuit (IC). The STI features can be filled with a dielectric film such as a flowable oxide deposited using flowable chemical vapor deposition (FCVD) or other methods. The flowable oxide provides a liquid-like filling behavior.

[0005] The quality of the flowable oxide film is limited by a high silanol content, which makes the flowable oxide film porous. The silanol bonds in the flowable oxide film are removed by annealing in a high-temperature furnace, exposure to UV treatment, or plasma annealing. The effectiveness of each of these methods is limited due to a low heat budget and a poor penetration depth into the flowable oxide film. Conventional plasma annealing cannot be used because of a high sputtering rate, which can damage the film.

[0006] In some applications, the aspect ratio (AR) of the trench can be as high as 8:1, and the opening of the trench may be narrowed to about 20 nm. Achieving void-free STI filling is important because the film can be further processed in subsequent integration steps. Subsequent processing may expose the voids. In some examples, the voids may be inadvertently filled with a conductive material, which may result in a short circuit.

[0007] The densification process should be able to achieve a fully densified film down to the bottom portion of the trench, or until the point where the wet chemicals can reach during subsequent chemical mechanical polishing (CMP) or other wet integration steps. SUMMARY OF THE INVENTION

[0008] A method for densifying a dielectric film on a substrate includes: disposing a substrate including the dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling the pressure in the substrate processing chamber to a pressure greater than or equal to a predetermined pressure; and providing a first power level to a coil at a first frequency to generate a plasma in the substrate processing chamber. The coil is disposed around at least a portion of the outer surface of the substrate processing chamber. The method further includes densifying the dielectric film for a predetermined time. The pressure and the first power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film.

[0009] In other features, the method includes providing a second power level to the coil at a second frequency while providing the first power level at the first frequency.

[0010] The method includes providing a third power level to the substrate support at a third frequency while providing the first power level at the first frequency and the second power level at the second frequency. The predetermined pressure, the first power level, the second power level, and the third power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film.

[0011] In other features, the predetermined pressure is greater than or equal to 40 mTorr. The first power level is greater than or equal to 5000 W, and the first frequency is in the range of 340 kHz to 375 kHz. The third power level is less than or equal to 2000 W, and the third frequency is 13.56 MHz. The second frequency is in the range of 420 kHz to 460 KHz.

[0012] In other features, the first power level is greater than 5000 W, the third power level is less than or equal to 2000 W, and the predetermined pressure is greater than or equal to 40 mTorr.

[0013] In other features, the first power level is between 6000 W and 8000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than 2000 W. During the densification process of the dielectric film, the temperature of the substrate is below 570 °C. The dielectric film includes a flowable oxide film.

[0014] A method for densifying a dielectric film on a substrate includes: disposing a substrate including the dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling the pressure in the substrate processing chamber to a pressure greater than or equal to 40 mTorr; and applying a first power level at a first frequency and a second power level at a second frequency to a coil to generate a plasma in the substrate processing chamber. The coil is disposed around an outer surface of the substrate processing chamber. The method further includes applying a third power level to the substrate support at a third frequency; and densifying the dielectric film for a predetermined time. The first power level is greater than or equal to 5000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than or equal to 2000 W.

[0015] Among other features, the first frequency is in the range of 340 kHz to 375 kHz, the second frequency is in the range of 420 kHz to 460 kHz, and the third frequency is 13.56 MHz. The first power level is between 6000 W and 8000 W. The temperature of the substrate is below 570 °C during densification of the dielectric film. The dielectric film includes a flowable oxide film.

[0016] Specifically, some aspects of the present invention can be set forth as follows: 1. A method for densifying a dielectric film on a substrate, comprising: disposing a substrate including the dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling the pressure in the substrate processing chamber to a pressure greater than or equal to a predetermined pressure; applying a first power level at a first frequency to a coil to generate a plasma in the substrate processing chamber, wherein the coil is disposed around at least a portion of an outer surface of the substrate processing chamber; and densifying the dielectric film for a predetermined time, [[ID=IP19]] wherein the pressure and the first power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film. 2. The method according to clause 1, further comprising applying a second power level at a second frequency to the coil while applying the first power level at the first frequency. 3. The method according to clause 2, further comprising applying a third power level to the substrate support at a third frequency while applying the first power level at the first frequency and the second power level at the second frequency. 4. The method according to clause 3, wherein the predetermined pressure, the first power level, the second power level, and the third power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film. 5. The method according to clause 1, wherein the predetermined pressure is greater than or equal to 40 mTorr. 6. The method according to clause 1, wherein the first power level is greater than or equal to 5000 W, and the first frequency is in the range from 340 kHz to 375 kHz. 7. The method according to clause 3, wherein the third power level is less than or equal to 2000 W, and the third frequency is 13.56 MHz. 8. The method according to clause 2, wherein the second frequency is in the range from 420 kHz to 460 KHz. 9. The method according to clause 3, wherein the first power level is greater than 5000 W, the third power level is less than or equal to 2000 W, and the predetermined pressure is greater than or equal to 40 mTorr. 10. The method according to clause 3, wherein the first power level is between 6000 W and 8000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than 2000 W. 11. The method according to clause 1, wherein the temperature of the substrate is lower than 570 °C during densification of the dielectric film. 12. The method according to clause 1, wherein the dielectric film comprises a flowable oxide film. 13. A method for densifying a dielectric film on a substrate, comprising: placing a substrate including the dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling the pressure in the substrate processing chamber to a pressure greater than or equal to 40 mTorr; applying a first power level at a first frequency and a second power level at a second frequency to a coil to generate a plasma in the substrate processing chamber, wherein the coil is disposed around an outer surface of the substrate processing chamber; applying a third power level to the substrate support at a third frequency; and densifying the dielectric film for a predetermined time, wherein the first power level is greater than or equal to 5000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than or equal to 2000 W. 14. The method according to clause 13, wherein the first frequency is in the range of 340 kHz to 375 kHz, the second frequency is in the range of 420 kHz to 460 kHz, and the third frequency is 13.56 MHz. 15. The method according to clause 13, wherein the first power level is between 6000 W and 8000 W. 16. The method according to clause 13, wherein the temperature of the substrate is below 570 °C during densification of the dielectric film. 17. The method according to clause 13, wherein the dielectric film comprises a flowable oxide film.

[0017] Other application areas of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure will be more fully understood from the detailed description and the drawings, wherein:

[0019] Figure 1 is a side cross-sectional view of an example of a substrate including shallow trench isolation features according to the present disclosure;

[0020] Figure 2 is a side cross-sectional view of an example of a substrate after filling the features with a flowable oxide film according to the present disclosure Figure 1 ;

[0021] Figure 3 is a side cross-sectional view of an example of a substrate after performing a densification method according to the present disclosure Figure 2 ;

[0022] Figure 4 is a functional block diagram of an example of a substrate processing chamber for densifying a flowable oxide film according to the present disclosure;

[0023] Figure 5 is a flowchart showing an example of a method for densifying a flowable oxide film according to the present disclosure;

[0024] Figure 6 is a graph showing an example of the relationship between the sputtering rate and the low-frequency power supplied to the coil;

[0025] Figure 7 is a graph showing an example of the relationship between the sputtering rate and the pressure;

[0026] Figure 8 is a graph showing an example of the relationship between the sputtering rate and the high-frequency power supplied to the substrate support; and

[0027] Figure 9 An example of wet etch rate ratio (WERR) as a function of etch thickness is shown.

[0028] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0029] The present disclosure relates to systems and methods for densifying dielectric films, such as flowable oxide films deposited within features. In some examples, the features include shallow trench isolation (STI). During plasma annealing in an inductively coupled plasma (ICP) chamber, plasma source conditions are modified to provide high plasma source power, which minimizes plasma voltage and sputtering rate. In some examples, high chamber pressure is used to reduce mean free path and ion energy. The use of high plasma power and high pressure allows film densification to occur without sputtering.

[0030] In some examples, RF bias power is provided to the substrate support to enhance penetration depth into the dielectric film. The RF bias power can be provided at the same frequency as the coil power or at a different frequency than the coil power. During densification as described herein, the temperature of the substrate can be maintained below 570°C, which is lower than conventional thermal annealing (at approximately 900°C). In some examples, a plasma gas mixture comprising helium and oxygen is used to accelerate the removal of silanols from the film and improve penetration depth compared to non-oxidizing plasma gas mixtures.

[0031] The substrate processing system described herein reduces the plasma voltage (V p ) and substrate voltage (V w ) to use a "soft" plasma. The energy supplied to the substrate is equal to q*N i *(V p -V w ), where Ni is the ion density, V p is the plasma voltage, q is a calibration factor based on chamber design, power efficiency, etc., and V w is the chip voltage. If (V p -V w ) is higher than the sputtering threshold (about 20V), sputtering occurs. i )Reduced (V p -V w ) and produces a "soft" plasma.

[0032] Now refer to Figures 1-3 , the STI features are filled with a dielectric film, and the dielectric film is densified. Figure 1In this case, the substrate 50 includes STI features 52 having sidewalls 54 and bottoms 56. In Figure 2 In this case, a dielectric film 58 such as a flowable oxide film is deposited in the STI features 52. In Figure 3 In this case, the dielectric film is densified to produce a densified dielectric film 58'.

[0033] Now referring to Figure 4 , the substrate processing chamber 100 can be used to perform the densification described above and below. Although a specific chamber is shown, other inductively coupled plasma (ICP) chambers can be used. The substrate processing chamber 100 includes a hemispherical dome 104 and a substrate support 112 for supporting the substrate 114. Although the hemispherical dome 104 is shown, the substrate processing chamber 100 can have other shapes including oval, flat top, etc. In some examples, the substrate support 112 includes an electrostatic chuck (ESC), but other substrate supports can also be used.

[0034] A coil 116 is disposed around the outer surface of the hemispherical dome 104. One or more upper gas injectors 120 are disposed in the upper portion of the hemispherical dome 104 to inject a process gas mixture in a downward and / or outward direction. One or more lower gas injectors 124 are disposed in the lower portion of the hemispherical dome 104 to inject a process gas mixture in an upward and / or inward direction relative to the hemispherical dome 104 and the substrate 114. By way of example only, the lower gas injectors 124 can include 36 gas injectors evenly spaced around the lower perimeter of the hemispherical dome 104.

[0035] A gas delivery system 130 supplies the process gas mixture to the upper gas injectors 120 and the lower gas injectors 124. The gas delivery system 130 can include one or more gas sources, mass flow controllers, valves, and / or manifolds (not shown). An RF bias circuit 134 supplies RF power to the coil 116 to generate a plasma 118 within the hemispherical dome 104. A substrate support bias circuit 136 supplies RF power to the substrate support 112. A substrate support temperature control circuit 138 controls the temperature of the substrate support 112 during substrate processing. The substrate temperature control circuit 138 can include: a system for delivering heating and / or cooling fluid to flow channels within the substrate support 112, a resistive heater, and / or other devices for controlling the temperature of the substrate support 112.

[0036] A valve 144 and a pump 146 are provided to exhaust reactants from the processing chamber. In some examples, the pump 146 includes a variable speed pump. In some examples, the pump 146 includes a turbo pump. The speed of the pump 146 is changed to set the pressure within the substrate processing chamber 100. Open-loop or closed-loop feedback can be used to control the pressure inside the substrate processing chamber 100.

[0037] If a closed-loop feedback is used, a pressure sensor 148 can be used to measure the pressure inside the substrate processing chamber 100. The controller 140 can be in communication with the variable speed pump 146 to control the pressure inside the substrate processing chamber 100 based on the measured pressure. If an open-loop feedback is used, the speed of the pump 146 is used to control the pressure inside the substrate processing chamber 100. A lower pump speed corresponds to a higher pressure, while a higher pump speed corresponds to a lower pressure. Additionally, the controller 140 can be used to control the timing and delivery of the process gas mixture from the gas delivery system 130, and to control the power supplied to the coil 116 and the substrate support 112.

[0038] Although specific examples of operating parameters and gas mixtures are described below, other operating parameters and gas mixtures can also be used. In some examples, the plasma gas mixture includes helium (He) and oxygen (O). In some examples, molecular oxygen (O2), carbon dioxide (CO2), nitrous oxide (N2O), nitric oxide (NO), ozone (O3), water (vapor) (H2O), hydrogen peroxide (H2O2), or other suitable oxygen-containing gases can be used to supply oxygen.

[0039] For example, when using H2 and O2 gases, He and O2 produce VUV of different wavelengths. The VUV emission of He is ~58 nm, and the VUV emission of O2 is ~130 nm. Other process gases can include Ar at ~105 nm and ~107 nm, molecular nitrogen (N2) at ~120 nm, and molecular hydrogen (H2) at ~121 nm. A relatively low substrate support bias avoids film damage due to sputtering.

[0040] In some examples, He is supplied at 720 sccm, and O2 is provided at 500 sccm. The pedestal is arranged approximately 1.2” from the injection position of the lower gas injector 124, which roughly corresponds to the lower position of the plasma. The coil 116 is excited with RF power.

[0041] In some examples, RF power is supplied to the coil 116 at a single frequency in the range between 340 - 460 kHz and at a power level greater than 10 kW. In some examples, RF power can be supplied to the coil 116 at two or more different frequencies. For example, low frequency (LF) and medium frequency (MF) can be used. In some examples, the substrate support is biased with RF power at high frequency (HF). In some examples, the LF power has a frequency in the range from 340 to 375 kHz, and the MF power has a frequency from 420 to 460 kHz, but other frequencies can also be used. In some examples, the HF power has a frequency of 13.56 MHz, but other frequencies can also be used.

[0042] In the first example, the pressure inside the chamber is maintained at 50 mTorr, the LF power is 7000 W, the MF power is 4000 W, the HF power is 0 W, and the processing cycle is 300 seconds, although other power levels, pressures, and times may be used. During the densification process, the substrate temperature is approximately 520 °C.

[0043] In the second example, the pressure inside the chamber is maintained at 50 mTorr, the LF power is 7000 W, the MF power is 4000 W, the HF power is 2000 W, and the processing cycle is 600 seconds, although other power levels, pressures, and times may be used. During the densification process, the substrate temperature is approximately 536 °C.

[0044] In other examples, the LF power is greater than or equal to 5000 W, the HF power is less than or equal to 2000 W, and the chamber pressure is greater than or equal to 40 mTorr. In other examples, the LF power is in the range between 6000 W and 8000 W, the MF power level is in the range between 3000 W and 5000 W, and the HF power level is less than or equal to 2000 W.

[0045] Now refer to Figure 5 , which shows a method 200 for densifying a dielectric film in STI features. At 204, a substrate is disposed in a processing chamber. The substrate includes features filled with a dielectric film such as a flowable oxide film. At 208, the chamber pressure is maintained at a predetermined value greater than or equal to 40 mTorr. At 212, a gas mixture is supplied to the processing chamber. The gas mixture includes oxygen and helium (He). At 216, power (including LF and MF power) is supplied to a coil. At 220, HF power is supplied to a substrate support. At 224, a control determines whether the densification cycle has ended. If 224 is false, the method returns to 208. Otherwise, the method ends.

[0046] Now refer to Figures 6-9 , where the sputtering rate is shown as a function of various input parameters (e.g., LF power, chamber pressure, and HF power). In Figure 6 , the sputtering rate is shown as a function of LF power while keeping the HF power at 4 kW and the chamber pressure at 5 mTorr. It can be seen that at an LF power of approximately 5000 W, the sputtering rate significantly decreases. In Figure 7 , the sputtering rate is shown as a function of chamber pressure while keeping the HF power at 0 W and maintaining the LF power at 11 kW. It can be seen that at pressures greater than approximately 40 mTorr, the sputtering rate significantly decreases. In Figure 8 , the sputtering rate is shown as a function of HF power. It can be seen that the sputtering rate begins to increase when the HF power level is above 2000 W.

[0047] Now refer to Figure 9 , for a thickness less than or equal to a wet etch rate ratio (WERR) of less than 3 can be achieved using the above-described first exemplary parameter (no substrate support bias). For a thickness of a WERR of less than 2 can be achieved using the second exemplary parameter described above.

[0048] The foregoing description is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses. The broad teachings of the present disclosure can be implemented in a variety of forms. Thus, while the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited since other modifications will become apparent upon study of the drawings, the specification, and the appended claims. It should be understood that one or more steps in a method can be performed in a different order (or concurrently) without changing the principles of the present disclosure. Additionally, while each embodiment is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure can be implemented in and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more of the embodiments with each other remain within the scope of the present disclosure.

[0049] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.), and the various terms include "connected," "joined," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." Unless the relationship between the first and second elements is explicitly described as "direct," when such a relationship is described in the foregoing disclosure, the relationship can be a direct relationship, where there are no other intervening elements between the first and second elements, but can also be an indirect relationship, where there is one or more intervening element(s) (spatially or functionally) between the first and second elements. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C) using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0050] In some implementations, the controller is part of a system, which can be part of the above examples. Such systems can include semiconductor processing equipment, which includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestal, gas flow system, etc.). These systems can be integrated with electronics for controlling their operations before, during, and after the processing of semiconductor wafers or substrates. The electronics can be referred to as a "controller", which can control various components or sub-components of one or more systems. Depending on the processing requirements and / or system type, the controller can be programmed to control any of the processes disclosed herein, any process including the delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer in and out of the tool and other transfer tools and / or load locks connected to or interfacing with a particular system.

[0051] Broadly speaking, the controller can be defined as electronics having various integrated circuits, logic, memory, and / or software for receiving instructions, issuing instructions, controlling operations, enabling cleaning operations, enabling endpoint measurements, etc. The integrated circuits can include chips in the form of firmware storing program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions delivered to the controller or system in the form of various individual settings (or program files), the individual settings (or program files) defining the operating parameters for performing a specific process on or for a semiconductor wafer. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or die of a wafer.

[0052] In some implementations, the controller can be part of a computer that is integrated with, coupled to, otherwise networked to the system, or a combination thereof. For example, the controller can be in the "cloud" or in all or part of a wafer fab host system, which can allow remote access to wafer processing. The computer can implement remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, study trends or performance metrics from multiple manufacturing operations, to change the parameters of the current process, set the process steps to follow the current process, or initiate a new process. In some examples, a remote computer (e.g., a server) can provide a process recipe to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that enables the input or programming of parameters and / or settings, which are then conveyed from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify the parameters for each process step to be performed during one or more operations. It should be understood that the parameters can be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers that are networked together and work towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such a purpose is one or more integrated circuits on a chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer), which combine to control the process on the chamber.

[0053] Example systems can include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, an orbit chamber or module, and any other semiconductor processing system that can be associated with or used for the manufacture and / or preparation of semiconductor wafers.

[0054] As described above, depending on one or more process steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a host computer, another controller, or tools used in the material transport that shuttles wafer containers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

Claims

1. A method for densifying a dielectric film on a substrate, comprising: placing a substrate including a dielectric film on a substrate support in a substrate processing chamber; supplying a gas mixture including helium and oxygen to the substrate processing chamber; controlling the pressure in the substrate processing chamber to a pressure greater than or equal to a predetermined pressure; applying a first power level to a coil at a first frequency to generate a plasma in the substrate processing chamber, wherein the coil is disposed around at least a portion of an outer surface of the substrate processing chamber; while applying the first power level at the first frequency, applying a second power level to the coil at a second frequency; reducing the difference between the plasma voltage and the substrate voltage to less than or equal to a sputtering threshold; and densifying the dielectric film for a predetermined time, wherein the predetermined pressure and the first power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film.

2. The method according to claim 1, further comprising applying a third power level to the substrate support at a third frequency while applying the first power level at the first frequency and the second power level at the second frequency.

3. The method according to claim 2, wherein, The predetermined pressure, the first power level, the second power level and the third power level are selected to prevent sputtering of the dielectric film during densification of the dielectric film.

4. The method according to claim 1, wherein the predetermined pressure is greater than or equal to 40 mTorr.

5. The method according to claim 1, wherein the first power level is greater than or equal to 5000 W, and the first frequency is in the range from 340 kHz to 375 kHz.

6. The method according to claim 2, wherein the third power level is less than or equal to 2000 W, and the third frequency is 13.56 MHz.

7. The method according to claim 1, wherein the second frequency is in the range from 420 kHz to 460 kHz.

8. The method according to claim 2, wherein the first power level is greater than 5000 W, the third power level is less than or equal to 2000 W, and the predetermined pressure is greater than or equal to 40 mTorr.

9. The method according to claim 2, wherein the first power level is between 6000 W and 8000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than 2000 W; and the first frequency is in the range from 340 kHz to 375 kHz, the second frequency is in the range from 420 kHz to 460 kHz, and the third frequency is 13.56 MHz.

10. The method according to claim 1, wherein the temperature of the substrate is lower than 570 °C during densification of the dielectric film.

11. The method according to claim 1, wherein the dielectric film comprises a flowable oxide film.

12. A method for densifying a dielectric film on a substrate, comprising: placing a substrate including a dielectric film on a substrate support in a substrate processing chamber; Supply a gas mixture including helium and oxygen to the substrate processing chamber; Control the pressure in the substrate processing chamber to a pressure greater than or equal to 40 mTorr; While supplying a first power level to the coil at a first frequency, supply a second power level to the coil at a second frequency to generate a plasma in the substrate processing chamber, wherein the coil is arranged around the outer surface of the substrate processing chamber; Supply a third power level to the substrate support at a third frequency; And Densify the dielectric film for a predetermined time, wherein the first power level is greater than or equal to 5000 W, the second power level is between 3000 W and 5000 W, and the third power level is less than or equal to 2000 W; wherein the first frequency is in the range of 340 kHz to 375 kHz, the second frequency is in the range of 420 kHz to 460 kHz, and the third frequency is 13.56 MHz.

13. The method according to claim 12, wherein the first power level is between 6000 W and 8000 W.

14. The method according to claim 12, wherein the temperature of the substrate is below 570 °C during densifying the dielectric film.

15. The method according to claim 12, wherein the dielectric film includes a flowable oxide film.

16. A method for densifying a dielectric film on a substrate, comprising: Arrange a substrate including a dielectric film on a substrate support in a substrate processing chamber; Supply a gas mixture including helium and oxygen to the substrate processing chamber; Control the pressure in the substrate processing chamber to a pressure greater than or equal to a predetermined pressure; While supplying a first power level to the coil at a first frequency, supply a second power level to the coil at a second frequency to generate a plasma in the substrate processing chamber, wherein the coil is arranged around at least a part of the outer surface of the substrate processing chamber, wherein the first power level is in a first range, the second power level is in a second range, and wherein the first range and the second range are non-overlapping; Reduce the difference between the plasma voltage and the substrate voltage to less than or equal to the sputtering threshold; And Densify the dielectric film for a predetermined time, wherein the predetermined pressure and the first power level and the second power level are selected to prevent sputtering of the dielectric film during densifying the dielectric film.

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