Radical assisted deposition for low-k film repair

Abstract

Methods for repairing and replenishing carbon content of low-k dielectric films are provided. In some embodiments, the methods include generating plasma radicals in a remote plasma source, flowing a precursor gas comprising a recovery precursor into a processing region, and exposing the precursor gas and a low-k film on a substrate in the processing region to plasma radicals from the remote plasma source to decrease a k-value and increase a carbon content of the low-k film.

Description

RADICAL ASSISTED DEPOSITION FOR LOW-K FILM REPAIR BACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to processes for processing low-k dielectric films. More specifically, embodiments described herein relate to processes for repairing and replenishing carbon content of low-k dielectric films.Description of the Related Art

[0002] The dielectric constant (k) of dielectric films in semiconductor fabrication is continually decreasing as device scaling continues. Minimizing integration damage on low dielectric constant (low-k) films is important to be able to continue decreasing feature sizes. However, as feature sizes shrink, improvement in the resistive capacitance and reliability of dielectric films becomes a serious challenge.

[0003] During back end of line (BEOL) integration processing operations, low-k dielectric films often suffer damage that can ultimately lead to larger undesirable resistive-capacitive (RC) delays and change in structure dimensions. For example, in processing operations such as etching, ashing, and wet cleaning of the low-k dielectric films, the process steps cause a reduction in carbon (methyl groups) and introduce undesirable silanol species (i.e. Si-OH bonds) which increase the dielectric constant (k-value) and make the low-k film surface more hydrophilic. Current techniques for low-k film repair have been successful in lowering increased k-values and recovery hydrophobicity. However, for porous low-k films that are also susceptible to carbon loss due to exposure to plasma, such methods are unable to replenish the lost carbon. In order to maintain the integrity of the low-k dielectric films, a method of low-k film repair that restores carbon loss by the low-k film is needed.SUMMARY

[0004] Embodiments described herein generally relate to processes for processing low-k dielectric films. More specifically, embodiments described herein relate to processes for repairing low-k dielectric films.

[0005] In an embodiment, a method for processing a substrate is provided. The method includes generating plasma radicals in a remote plasma source, and flowing a precursor gas into a processing region of a process chamber. The precursor gas comprises a recovery precursor. The method also includes exposing the precursor gas and a low-k film on the substrate in the processing region to plasma radicals from the remote plasma source to decrease a k-value and increase a carbon content of the low-k film.

[0006] In another embodiment, a method for processing a substrate disposed in a processing region of a process chamber is provided. The method includes exposing a low-k film on the substrate to a precursor gas comprising a recovery precursor. The method also includes applying a RF power to the precursor gas and pulsing the RF Power to generate a pulsed plasma in the processing region. In some embodiments, the RF Power is pulsed at a pulse frequency between about 10 Hz to about 20 kHz, and at a duty cycle between about 10% and about 90%. A low-k film on the substrate is then exposed to the pulsed plasma to decrease a k-value and increase a carbon content of the low-k film.

[0007] In a further embodiment, a method for processing a substrate is provided. The method includes disposing a substrate in a processing region of a process chamber, the substrate comprising a low-k film formed over an etch stop layer, and patterning the substrate to form one or more trenches and / or one or more vias in the low-k film on the substrate. The method also includes generating plasma radicals in a remote plasma source, and flowing a precursor gas comprising a recovery precursor into the processing region. The precursor gas and the low-k film on the substrate in the processing region are then exposed to plasma radicals from the remote plasma source to decrease a k-value and increase a carbon content of the low-k film.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of scope, as the disclosure may admit to other equally effective embodiments.

[0009] FIG. 1 is a schematic cross-sectional view of a process chamber that may be used to perform the methods described herein, according to certain embodiments;

[0010] FIG. 2 is a flow chart depicting an exemplary method of processing a low-k dielectric film on a substrate using the process chamber illustrated in FIG. 1, according to certain embodiments;

[0011] FIGS. 3A and 3B are schematic cross-sectional side views of an exemplary low-k film the method of FIG. 2 may be performed on, according to certain embodiments;

[0012] FIGS. 4A and 4B are molecular views of a low-k film prior to performing the method 200, according to one or more embodiments;

[0013] FIG. 5 is a flow chart depicting an exemplary method of processing a low-k dielectric film on a substrate, according to certain embodiments;

[0014] FIG. 6 is a graph showing the XPS depth profile of an exemplary low-kfilm, according to certain embodiments

[0015] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0016] Embodiments described herein generally relate to processes for processing low-k dielectric films. More specifically, embodiments described herein relate to processes for repairing low-k dielectric films and restoring carbon loss. Certain details are set forth in the following description and figuresto provide a thorough understanding of various embodiments of the disclosure. Other details describing well-known methods and systems often associated with the deposition of thin films are not set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments.

[0017] During BEOL processing operations, the application of plasma processing on porous low-k dielectric films can cause integration related low-k damage, such as material modification in the form of loss of carbon groups and the formation of Si-OH units. For example, during conventional damascene integration, low-k damage can occur during the patterning processes for forming metal trenches and / or vias where the etch or resist strip plasma can cause carbon depletion and increased hydrophilicity in the low-k film accompanied by increased moisture uptake. As a result, the electrical properties of the low-k film, such as k-value, leakage current and breakdown voltage can be significantly compromised. If not addressed, these changes in the low-k film can lead to device failure during reliability qualifications. While conventional techniques for low-k film repair may be used to replenish carbon methyl groups and recover the hydrophobicity of low-k films, such methods are unable to replenish carbon loss of damaged low-k film. Without being bound by theory, it is believed that replenishing carbon loss may restore the atomic composition of the low-k film to a restored state that is the same or substantially similar to its pristine / undamaged state, as well as decrease the porosity of the damaged low-k film that could lead to undesired non-uniform ity in subsequent deposition processes. Accordingly, the techniques for repairing low-k dielectric films described herein provide for decreasing the k-value, restoring the hydrophobic character, and replenishing the carbon content of damaged low-k films.

[0018] Many of the details, components and other features described herein are merely illustrative of particular embodiments. Accordingly, other embodiments can have other details, components, and features without departing from the spirit or scope of the present disclosure. In addition, further embodiments of the disclosure can be practiced without several of the details described below.

[0019] Embodiments of the present disclosure provide methods for repairing damaged low-k films. In particular, the methods of the present disclosure utilize radical assisted deposition processes to replenish the carbon content of damaged low-k films. In an embodiment, the methods may utilize plasma radicals generated by a RF pulsing plasma to provide the dominant excitation to a recovery precursor. In some embodiments, the processing of the damaged low-k film may be performed using either a remote or a direct pulsing RF plasma. In certain embodiments, the recovery precursor includes a hydrocarbon compound, such as C2H4, to fill the porosities of the damaged low-k film with carbon atoms and replenish the carbon content of the low-k film. In other embodiments, the plasma radicals may be generated from a remote plasma formed from an inert gas.

[0020] FIG. 1 is a schematic cross-sectional view of a process chamber 100 for performing methods of the present disclosure, according to certain embodiments. In an embodiment, the process chamber 100 may be used for performing the method 200 described below to repair and replenish the carbon content of damaged low-k films on a substrate.

[0021] In an embodiment, the process chamber 100 includes a lid assembly 102 having a remote plasma source. In certain embodiments, the remote plasma source may be any suitable source that is capable of generating plasma radicals from a radical forming gas, such as Ar gas. The remote plasma source may be a radio frequency (RF) or very high radio frequency (VHRF) capactively coupled plasma (CCP) source, an inductively coupled plasma (ICP) source, a microwave induced (MW) plasma source, a DC glow discharge source, an electron cyclotron resonance (ECR) chamber, or a high density plasma (HDP) chamber. Alternatively, the remote plasma source may be an ultraviolet (UV) source or the filament of a hot wire chemical vapor deposition (HW-CVD) chamber.

[0022] As shown in FIG. 1, the remote plasma source comprises a remote plasma region 110 disposed between a faceplate 114 and an ion blocker 120. The faceplate 114 is part of the lid assembly 102, which also includes a lid rim 116 and a dual-channel showerhead 118. The ion blocker 120, lid rim 116, andthe dual-channel showerhead 118 in turn define a remote radical region 111. The faceplate 114 includes an RF feed structure for coupling an RF power source 108 to the faceplate 114. The RF power source 108 is coupled to the RF feed structure via a match network 112. The RF power source 108 is configured to apply RF power to create a differential between the faceplate 114 and the ion blocker 120 to form a capacitively coupled plasma in the remote plasma region 110.

[0023] The RF power source 108 can provide RF power at a frequency and power as appropriate for a particular application based on the processing gases used and the radical being formed. For example, the RF power source 108 may illustratively be capable of producing up to about 6000 W (but not limited to about 6000 W) at a fixed or tunable frequency in a range from about 5 Hz to about 62 MHz, such about 13.56 MHz, although other frequencies and powers may be provided as desired for particular applications. When RF current is fed to faceplate 114 via the RF feed structure from the RF power source 108, a capactively coupled plasma can be formed inside the remote plasma region 110 from an electric field generated between the faceplate 114 and the ion blocker 120.

[0024] The capactively coupled plasma may be generated from a radical forming gas flowed to the remote plasma region 110 from one or more gas sources. When receiving power from the RF power source 108, the electric field energizes and ignites the radical forming gas to form the plasma. One or more radical forming gases may enter the remote plasma region 110 via the one or more gas inlets 106. For example, the one or more gas inlets 106 may be coupled at a second end to an upstream gas source 119 of radical forming gases that may be used to generate radicals in the remote plasma region 110 of the process chamber 100. In an embodiment, which may be combined with other embodiments, the radical forming gases for generating the plasma radicals may consist of one or more inert gases, such as argon (Ar) gas, helium (He) gas, krypton (Kr) gas, neon (Ne) gas, or combinations thereof.

[0025] The ion blocker 120, showerhead 118, and remote radical region separate the remote plasma region 110 from a processing region 128 ofthe process chamber 100, and provide for the plasma generated in the remote plasma region 110 to avoid directly exciting precursor gases in the processing region 128 of the process chamber 100. Plasma power may essentially be applied only to the remote plasma region 110, in embodiments, to ensure that the generated plasma radicals provide the dominant excitation to the recovery precursor in the processing region 128.

[0026] In an embodiment, the ion blocker 120 has a plurality of openings 123 that allow radicals to flow from the remote plasma region 110 to the remote radical region 111. Because ions from the generated plasma are charged, the polarized ion blocker 120 acts as a barrier to ion passage through the openings 123. Since radicals are uncharged, the polarized ion blocker 120 has a minimal, if any, impact on the movement of the radicals through the openings 123 enabling radicals from the plasma generated in the remote plasma region 110 to pass through the ion blocker 120 to the remote radical region 111. In an embodiment, the ion blocker 120 generates a flow of radicals into the remote radical region 111 that is substantially free of ions. From the remote radical region 111 , the flow of radicals then pass through channels in the showerhead 118 to the processing region 128.

[0027] In some embodiments, which may be combined with other embodiments, the ion blocker 120 is polarized relative to the showerhead 118 using a voltage regulator 104. The voltage regulator 104 may configured to provide a direct current (DC) polarization of the ion blocker 120 relative to the showerhead 118 in the range of about ±2V to about ±100V, or in the range of about ±5V to about ±50V. Stated differently, the ion blocker 120 is polarized relative to the showerhead 118 in the range of about 2V to about 100V, or in the range of about 5V to about 50V, with either a positive or negative bias.

[0028] In an embodiment, which can be combined with other embodiments, radicals and neutral species from the plasma generated in the remote plasma region 110 may pass through a first plurality of channels 124 extending through the showerhead 118 to enter the processing region 128. The showerhead 118 further includes a second plurality of channels 126 that is smaller in diameter than the first plurality of channels 124. The second plurality of channels 126connects to an internal volume (not shown) of the showerhead 118 and is not in fluid communication with the first plurality of channels 124. In an embodiment, one or more precursor gas source 121 may be coupled to the dual-channel showerhead 118 in fluid communication with inner volume of the showerhead 118 and the second plurality of channels 126. The precursor gas source 121 may provide a precursor gas, such as a silicon containing gas, to the dual-channel showerhead 118. The precursor gas from the precursor gas source 121 may flow through inner volume of the dual-channel showerhead 118 to the processing region 128 via the second plurality of channels 126.

[0029] Since the first plurality of channels 124 is not in fluid communication with the internal volume of the showerhead 118, the radicals passing through the first plurality of channels 124 from the remote radical region 111 are not exposed to the precursor gas flowing through the second plurality of channels 126 of the dual-channel showerhead 118. Because the showerhead 118 contains two channels that are not in fluid communication of each other, the showerhead 118 is a dual-channel showerhead 118. In certain embodiments, each of the first plurality of channels 124 has an inner diameter of about 0.10 to about 0.35 in. In certain embodiments, which can be combined with other embodiments, each of the second plurality of channels 126 has an inner diameter of about 0.01 in to about 0.04 in. In some embodiments, the dualchannel showerhead 118 may be heated or cooled. In one embodiment, which can be combined with other embodiments, the dual-channel showerhead 118 is heated to a temperature of about 100°C to about 250°C during processing. In another embodiment, which can be combined with other embodiments, the dual-channel showerhead 118 is cooled to a temperature of about 25°C to about 75°C.

[0030] In addition to the ion blocker 120, the first plurality of channels 124 of the showerhead 118 may be configured to assist in suppressing the migration of ionically-charged species out of the remote radical region 111 while allowing uncharged neutral species or radicals to pass through the showerhead 118 into the processing region 128. For example, the aspect ratio of the first plurality of channels 124 (i.e., the inner diameter to length) and / or the geometry of the first plurality of channels 124 may be controlled so that the flow of ionically-chargedspecies in the activated gas passing through showerhead 118 is reduced. In another example, the first plurality of channels 124 in showerhead 118 may include a tapered portion that faces the remote radical region 111, and a cylindrical portion that faces the processing region 128. The cylindrical portion may be proportioned and dimensioned to control the flow of ionic species passing into the processing region 128.

[0031] In another embodiment, which may be combined with other embodiments described herein, the ion blocker 120 may be omitted and an adjustable electrical bias may be applied to showerhead 118 as an additional means to control the flow of ionic species through showerhead 118. In some embodiments, which may be combined with other embodiments, the uncharged species and radicals may include highly reactive species that are transported with less-reactive carrier gas through the first plurality of channels 124. It is contemplated that in some examples, the uncharged species and radicals may flow through the first plurality of channels 124 without a carrier gas.

[0032] In another embodiment, which may be combined with other embodiments described herein, the ion blocker 120 may be omitted and the remote plasma source may be configured to generate a pulsed RF plasma in the remote plasma region 110 to control radical generation in the remote plasma region 110. Pulsed RF plasma can be used to obtain high-precision plasma processing to control the dynamics of radical formation and the resulting ion radical ratio in the generated plasma. Accordingly, in some embodiments, the RF power source 108 may be a pulsed RF power source operable in a pulse mode tailored to generate radicals by the pulsed plasma. When in pulse mode, the RF power source 108 may be pulsed at a pulse frequency between about 10 Hz to about 20 kHz, such as about 1 kHz. The RF power source 108 may be operated at a duty cycle (e.g., the percentage of on time during the total of on time and off time in a given cycle) of between about 10% and about 90%, such as between about 15% and about 60%, between about 50% and about 80%, between about 20% and about 50%, or about 30%.

[0033] As noted above, the ion blocker 120 and showerhead 118 are configured to reduce or suppress the flow of ionic species from the generatedplasma through the showerhead 118 so that only the uncharged species and / or radicals enter the process region 128 to react with the precursor gas and substrate. Accordingly, by tuning processing parameters and controlling the radical and ionic species in the processing region 128 (either by utilizing the ion blocker 120 and / or showerhead 118, or pulsed RF plasma as described above), the methods described herein provide increased control over the reaction of the gas mixture and deposition characteristics of atomic carbon on the damaged low-k film in the processing region 128. For example, by limiting the makeup of the processing gas mixture in the processing region 128 to plasma radicals, processing parameters may be tuned to modulate the deposition rate of carbon in and on the damaged low-k film and the resulting film structure and corresponding carbon content % of the low-k film. It was also observed that tuning processing parameters to deposit and therefore alter the carbon content % of the damaged low-k film also provided for decreasing the k-value and restoring the hydrophobic character of the damaged low-k film.

[0034] The process chamber 100 may include the lid assembly 102, a chamber body 130, and a support assembly 132. The support assembly 132 may be at least partially disposed within the chamber body 130. The chamber body 130 may include a slit valve 135 to provide access to the interior of the process chamber 100. The chamber body 130 may include a liner 134 that covers the interior surfaces of the chamber body 130. The liner 134 may include one or more apertures 136 and a pumping channel 138 formed therein that is in fluid communication with a vacuum system 140. The apertures 136 provide a flow path for gases into the pumping channel 138, which provides an egress for the gases within the process chamber 100. Alternatively, the apertures and the pumping channel may be disposed in the bottom of the chamber body 130, and the gases may be pumped out of the process chamber 100 from the bottom of the chamber body 130.

[0035] The vacuum system 140 may include a vacuum port 142, a valve 144 and a vacuum pump 146. The vacuum pump 146 is in fluid communication with the pumping channel 138 via the vacuum port 142. The apertures 136 allow the pumping channel 138 to be in fluid communication with the processing region 128 within the chamber body 130. The processing region 128 is definedby a lower surface 148 of the dual-channel showerhead 118 and an upper surface 150 of the support assembly 132, and the processing region 128 is surrounded by the liner 134.

[0036] The support assembly 132 may include a support member 152 to support a substrate (not shown) for processing within the chamber body 130. The substrate may be any standard wafer size, such as, for example, 300 mm. Alternatively, the substrate may be larger than 300 mm, such as 450 mm or larger. The support member 152 may comprise AIN or aluminum, depending on operating temperature. The support member 152 may be configured to chuck the substrate, and the support member 152 may be an electrostatic chuck or a vacuum chuck.

[0037] The support member 152 may be coupled to a lift mechanism 154 through a shaft 156 which extends through a centrally-located opening 158 formed in a bottom surface of the chamber body 130. The lift mechanism 154 may be flexibly sealed to the chamber body 130 by bellows 160 that prevents vacuum leakage from around the shaft 156. The lift mechanism 154 allows the support member 152 to be moved vertically within the chamber body 130 between a process position and a lower, transfer position. The transfer position is slightly below the opening of the slit valve 135. During operation, the spacing between the substrate and the dual-channel showerhead 118 may be minimized in order to maximize radical flux at the substrate surface. For example, the spacing may be between about 100 mils and about 1,000 mils. The lift mechanism 154 may be capable of rotating the shaft 156, which in turn rotates the support member 152, causing the substrate disposed on the support member 152 to be rotated during operation. In certain embodiment, rotation of the substrate can help in improving deposition uniformity.

[0038] One or more heating elements 162 and a cooling channel 164 may be embedded in the support member 152. The heating elements 162 and cooling channel 164 may be used to control the temperature of the substrate during operation. The heating elements 162 may be any suitable heating elements, such as one or more resistive heating elements. The heating elements 162 may be connected to one or more power sources (not shown).The heating elements 162 may be controlled individually to have independent heating and / or cooling control on multi-zone heating or cooling. With the ability to have independent control on multi-zone heating and cooling, the substrate temperature profile can be enhanced at any giving process conditions. A coolant may flow through the cooling channel 164 to cool the substrate. The support member 152 may further include gas passages extending to the upper surface 150 for flowing a cooling gas to the backside of the substrate.

[0039] The function of the process chamber 100 can be controlled by a computing device 166. The computing device 166 may be one of any form of general purpose computer that can be used in an industrial setting for controlling various chambers and sub-processors. The computing device 166 includes a computer processor 168. The computing device 166 includes memory 170. The memory 170 may include any suitable memory, such as random access memory, read only memory, flash memory, hard disk, or any other form of digital storage, local or remote. The computing device 166 may include various support circuits 172, which may be coupled to the computer processor 168 for conventionally supporting the computer processor 168. Software routines, as required, may be stored in the memory or executed by a second computing device (not shown) that is remotely located.

[0040] The computing device 166 may further include one or more computer readable media (not shown). Computer readable media generally includes any device, located either locally or remotely, which is capable of storing information that is retrievable by a computing device. Examples of computer readable media useable with embodiments of the present embodiments include solid state memory, floppy disks, internal or external hard drives, and optical memory (CDs, DVDs, BR-D, etc). In one embodiment, the memory 170 may be the computer readable media. Software routines may be stored on the computer readable media to be executed by the computing device.

[0041] The software routines, when executed, transform the general purpose computer into a specific process computer that controls the chamber operation so that a chamber process is performed. Alternatively, the softwareroutines may be performed in hardware as an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware.

[0042] FIG. 2 is a schematic block diagram of a method 200 for substrate processing, according to one or more embodiments. FIGS. 3A and 3B are partial schematic side cross-sectional views of exemplary interconnect structures that may be processed utilizing the method 200, according to one or more embodiments. FIGS. 4A and 4B are molecular views of a low-k film 310 prior to performing the method 200, according to one or more embodiments.

[0043] Method 200 begins at operation 210 in which a substrate having a feature formed thereon, such as an interconnection structure 300 shown in FIG.3A, is disposed in a process chamber. The process chamber may be the process chamber 100 depicted in FIG. 1 , and the interconnection structure 300 may be disposed on the upper surface 150 of the support assembly 132 in the processing region 128. In an embodiment, the interconnection structure 300 includes a damaged low-k film 310 having a feature formed therein and disposed over an underlying layer 350. In some embodiments, the feature in the low-k film 310 may be a via 320 extending through the low-k film 310. Although only a single via 320 is shown, in some embodiments, the low-k film 310 may include a plurality of vias 320 extending therethrough.

[0044] As shown in FIG. 3A, the interconnect structure 300 includes the low-k film 310 and the via 320 formed over an etch stop layer 330 disposed over the underlying layer 350. In an embodiment, the underlying layer 350 includes a via having a copper fill layer 340 formed therein. The via 320 in the low-k film 310 may be vertically aligned over the copper fill layer 340 formed in the underlying layer 350, as shown in FIG. 3A. In other embodiments, the low-k film 310 of the interconnect structure 300 may alternatively be formed over a tungsten (W) fill layer in the underlying layer 350.

[0045] In other embodiments, method 200 may be used to process an interconnect structure with a different configuration and layers, such as an interconnection structure 301 with dual damascene levels as shown in FIG. 3B.The interconnection structure 301 includes a feature 321 formed in the damaged low-k film 310 with an aluminum oxide layer (AIO) 312, a SiOC layer 314, and the etch stop layer 330 disposed between the damaged low-k film 310 and the underlying layer 350.

[0046] In some embodiments, the interconnection structure 300 may be formed and the low-k film 310 damaged in the process chamber 100 prior to operation 210. For example, in such an embodiment, the processing to form the interconnection structure 300 in turn may cause the low-k film 310 of the substrate to be damaged. In some embodiments, the low-k film 310 may be damaged due to processing operations such as etching, ashing, wet cleaning operations, or combinations thereof. In an embodiment, the low-k film 310 may be damaged when processed to form the via 320. In such an embodiment, operation 210 may not be needed as the interconnection structure 300 may already be disposed in the process chamber 100. In other embodiments, the interconnection structure 300 may be formed and the low-k film 310 damaged in a different process chamber prior to being transferred and disposed in the process chamber 100 in operation 210.

[0047] FIG. 4A is a molecular view 310a of the as deposited low-k film 310 prior to being damaged by the etching of the via 320. As shown in FIG. 4A, the as deposited low-k film 310 has Si-0 bonds, Si-CHs bonds, and Si-H bonds. FIG. 4B is a molecular view 310b of the low-k film 310 after the via 320 is etched into the low-k film 310 and causing damage to the low-k film 310. As shown in FIG. 4B, the overall number of Si-CHs bonds in the low-k film 310 may be decreased resulting in loss of carbon content by the low-k film 310. Silanols (Si-OH bonds) are also formed on the low-k film 310 causing the low-k film 310 to undesireably become more hydrophilic and a k-value of the low-k film 310 to increase. For example, prior to being damaged, the low-k film 310 as shown in FIG. 4A may have a k-value of about 3.26 and carbon content % of about 24.6%. However, after the low-k film 310 is damaged, the k-value may increase to about 3.54 and the carbon content % may decrease to about 6.9%.

[0048] At operation 220, a radical forming gas is flowed from the upstream gas source 119 into the remote plasma region 110 of the process chamber 100.In certain embodiments, the radical forming gas comprises one or more inert gases, such as argon (Ar) gas, helium (He) gas, krypton (Kr) gas, neon (Ne) gas, or combinations thereof. In some embodiments, the radical forming gas comprises an argon gas and / or helium gas.

[0049] In certain embodiments, which can be combined with other embodiments, the radical forming gas in operation 220 for forming plasma radicals may be flowed into the remote plasma region 110 of the process chamber at a flow rate between about 50 seem and about 4000 seem, such as between about 50 seem and about 3000 seem, or between about 300 seem and about 2500 seem.

[0050] In operation 230, a remote plasma power is applied by the RF power source 108 to ignite the flowing radical forming gas and generate a remote plasma in the remote plasma region 110. The remote plasma generated in operation 230 includes formation of plasma radicals and other plasma effluents by the remote plasma using the radical forming gas flowed to the remote plasma source in operation 220. In an embodiment, the remote plasma can be generated by any suitable technique known to the skilled artisan including, but not limited to, capactively coupled plasma, inductively coupled plasma and microwave plasma. In some embodiments, the plasma is a capacitively coupled plasma generated in the remote plasma region 110 of the process chamber 100 by applying RF and / or DC power to the faceplate 114 to create a differential between the faceplate 114 and one or more of the ion blocker 120 or showerhead 118.

[0051] In an embodiment, the radical forming gas for generating the remote plasma comprises a hydrogen containing gas, such as hydrogen, H2O, or ammonia (NH3). In certain embodiments, the radical forming gas comprises one or more inert gases, such as argon (Ar) gas, helium (He) gas, krypton (Kr) gas, neon (Ne) gas, or combinations thereof. As used herein, plasma radicals refer to the molecules of the inert gas used excited to a metastable state. For example, when argon and helium gas is used, argon and helium ions and radicals are generated. The argon and helium ions are then filtered by the ionblocker such that only argon and helium radicals flow into the processing region for reacting with the precursor gas.

[0052] In certain embodiments, radicals from the radical forming gas may include one or more of hydrogen radicals, nitrogen radicals, NH radicals, helium radicals, argon radicals, krypton radicals, and neon radicals. As the remote plasma region 110 in process chamber 100 is separated from the processing region 128 by the ion blocker and dual-channel showerhead, the generated plasma in the remote plasma region 110 does not directly excite and react with the precursor gases in the processing region 128. In an embodiment, the radical forming gas in the remote plasma region 110 may be ignited into a remote plasma in operation 230 by applying RF power to the faceplate 114.

[0053] In an embodiment, the RF power applied in operation 230 for generating the remote plasma may be between about 50 Watts and about 2000 Watts, such as between about 100 Watts and about 1000 Watts, or between about 500 Watts and about 1500 Watts, such as about 800 Watts. The RF Power may be provided at a fixed or tunable frequency in a range from about 5 Hz to about 62 MHz, although other frequencies and powers may be provided as desired for particular applications. In certain embodiments, the RF power may be a high frequency RF power of approximately 13.56 MHz that is capable of producing either continuous or pulsed power, although other higher or lower frequencies and powers may be provided as desired for particular applications. For example, in an embodiment, the RF power source 108 may be pulsed at a pulse frequency between about 10 Hz to about 20 kHz, such as about 1 kHz. The RF power source 108 may be operated at a duty cycle (e.g., the percentage of on time during the total of on time and off time in a given cycle) of between about 10% and about 90%, such as about 30%.

[0054] In operation 240, a precursor gas comprising a recovery precursor is flowed from the precursor gas source 121 into the processing region 128 of the process chamber 100. Operation 240 includes exposing the interconnection structure 300 to the precursor gas. In an embodiment, the precursor gas may be flowed into the processing region 128 through the second plurality ofchannels 126 of the showerhead 118 in fluid communication with the precursor gas source 121.

[0055] The recovery precursor may include a molecule selected from Group 1 shown below. In Group 1 , R may be independently selected from a methyl group (Me), ethyl group (Et), isopropyl group (iPr), tertiary butyl group (tBu,) and hydrogen (H). R’ may be independently selected from an alkane, an alkene, and an alkyne. R’ may include between one and twenty carbon atoms.Group 1

[0056] In one or more embodiments, the precursor gas may be one of the molecules pictured in Group 1 Examples below.Group 1 Examples

[0057] In certain embodiments, the recovery precursor may include a molecule selected from Group 2. In Group 2, R may be independently selected from Me, Et, iPr, and tBu. R’ may be independently selected from an alkane, an alkene, and an alkyne. R’ may include between one and twenty carbon atoms.

[0058] In certain embodiments, the recovery precursor may include a molecule selected from Group 3. In Group 3, X may be chlorine (Cl), bromine (Br), or iodine (I). R’ may be independently selected from an alkane, an alkene, and an alkyne. R’ may include between one and twenty carbon atoms.Group 3

[0059] In certain embodiments, the recovery precursor may include a molecule selected from Group 4. In Group 4, R’ may be independently selected from an alkane, an alkene, and an alkyne. R’ may include between one and twenty carbon atoms.Group 4

[0060] In certain embodiments, the recovery precursor may include a molecule selected from Group 5. In Group 5, R and R’ may be independently selected from hydrogen, an alkane, an alkene, an alkyne, and an aryl. In embodiments where R and / or R’ contain carbon, R and R’ may include between one and twenty carbon atoms each.Group 5

[0061] In certain embodiments, the recovery precursor may include a molecule selected from Group 6. In Group 6, R, R’, and R” may be independently selected from hydrogen, an alkane, an alkene, an alkyne, and an aryl. In embodiments where R, R’, and / or R” contain carbon, R, R’, and R” may include between one and twenty carbon atoms each.Group 6

[0062] In certain embodiments, the recovery precursor may include a molecule selected from Group 7. In Group 7, R, R’, R”, and R’” may be independently selected from hydrogen, an alkane, an alkene, an alkyne, and an aryl. In embodiments where R, R’, R”, and / or R’” contain carbon, R, R’, R”, and R’” may include between one and twenty carbon atoms each.Group 7

[0063] In certain embodiments, the recovery precursor may include a molecule selected from Group 8. In Group 8, R and R’ may be independently selected from hydrogen, an alkane, an alkene, an alkyne, and an aryl. In embodiments where R and / or R’ contain carbon, R and R’ may include between one and twenty carbon atoms each.Group 8

[0064] In some embodiments, which can be combined with other embodiments, the precursor gas may further include a carrier gas, such as helium (He), argon (Ar), xenon (Xe), hydrogen (H2), nitrogen (N2), ammonia (NH3), nitric oxide (NO), or any combination thereof. In an embodiment, the recovery precursor may be flowed at a flow rate between about 100 mgm and about 2000 mgm. In an embodiment, the carrier gas may be flowed at a flow rate between about 1000 seem and about 5000 seem.

[0065] In operation 250, plasma effluents from the remote plasma, namely a flow of plasma radicals, are introduced into the processing region 128 to repair the low-k film 310. For example, plasma radicals formed in the remote plasma region 110 by the remote plasma are flowed into the processing region 128 to excite the precursor gas being flown into the processing region 128. As the plasma radicals from the remote plasma region 110 react with the recovery precursors of the precursor gas, carbon from the recovery precursors are deposited on and in the low-k film 310 to repair and replenish the carbon content of the low-k film 310. Without being bound by theory, carbon rich surfaces are generally considered more resistant to plasma-induced damage. It was also observed that exposure to the reaction between the recovery precursors and the plasma radicals in operation 250 decreased the k-value. In an embodiment, operation 250 decreased the k-value of the damaged low-k film to within about .05 of the original k-value of the low-k film 310 prior to the low-k film 310 being damaged.

[0066] In some embodiments, operation 250 may be performed at a temperature between about 75°C and about 500°C. In some embodiments, operation 250 may be performed for a period ranging from about 1 minute to about 10 minutes. In some embodiments, operation 240 may be performed at a pressure between about 1 Torr and about 10 Torr. In some embodiments, operation 240 may be performed with a gas flow of the recovery precursor ranging from about 100 mgm to about 2000 mgm. In certain embodiments, the flowing of the radical forming gas in operation 220 and / or the flowing of the precursor gas in operation 240 occurs concurrently with and / or is ongoing during operation 250 (e.g., to maintain the remote plasma and the supply ofprecursor gas in the processing region 128) as the low-k film 310 is repaired and its carbon content replenished.

[0067] In an embodiment, operation 240 may include polarizing the ion blocker 120 to filter plasma ions from the plasma radicals as plasma effluents are flowed from the remote plasma region 110. For example, when the ion blocker 120 is polarized, the passing of ions through the openings in the ion blocker 120 is reduced. The suppression of plasma ions by the ion blocker 120 creates a flow of plasma radicals substantially free of plasma ions from the remote plasma region 110 to the remote radical region 111. In an embodiment, the ion blocker 120 decreases the number of ions in the generated plasma from a first number in the remote plasma region 110 to a second number in the remote radical region 111. In some embodiments, the second number is less than or equal to about 50%, 40%, 30%, 20%, 10%, 5%, 2%, 1% or 0.5% of the first number.

[0068] In another embodiment, operation 240 may alternatively include pulsing the remote RF plasma in the remote plasma region 110 to control the formation of plasma radicals in the generated remote plasma. Pulsing the remote RF plasma in turn allows for tuning the ion radical ratio in the remote plasma so that the precursor gas in the processing region 128 is dominantly excited by plasma radicals from the remote plasma source as plasma effluents from the remote plasma region 110 flow into the processing region 128.

[0069] In an exemplary embodiment, the flow of plasma radicals from the remote plasma region 110 are introduced into the processing region 128 through the first plurality of channels 124 in the dual-channel showerhead 118. The first plurality of channels 124 enables the flow of plasma radicals to enter the processing region 128 without mixing with the precursor gas being flown into the processing region 128 through the second plurality of channels 126 of the showerhead 118.

[0070] During operation 250, carbon atoms from the precursor gas are deposited over and within the low-k film 310. In an embodiment, operation 250 may result in the deposition of a thin layer of carbon (not shown) over the low-k film 310. In an embodiment, operation 250 for processing the interconnection structure 300 may be performed until a predetermined thickness of the carbon layer is formed on the low-k film 310. In an embodiment, operation 250 may be performed for between about 1 min. and about 10 min. In some embodiments, the carbon layer may have a thickness between about 3 A and about 20 A, such as between about 5 A and about 10 A, such as about 6 A.

[0071] While a post-processing treatment may not be necessary to repair the low-k film 310 and replenish lost carbon, some embodiments of method 200 may include performing an optional post-processing treatment, for example, a UV curing process on the low-k film 310 at an operation 260. In some embodiments, method 200 may include halting a flow of the precursor gas prior to performing the post-processing treatment. The optional post-processing treatment in operation 260 includes exposing the low-k film 310 to ultraviolet (UV) light or radiation. In some embodiments, exposure to UV light in operation 260 may provide for modulating the % of carbon of the low-k film 310 replenished in operation 250. In some embodiments, UV light exposure may also provide for increasing the mechanical stability of the now repaired low-k film 310.

[0072] In some embodiments, the exposure to UV light may be performed in the same process chamber used for the repair of the low-k film 310. In some embodiments, the interconnection structure 300 may be transferred to another semiconductor processing chamber where the UV light exposure operation is performed.

[0073] In some embodiments, operation 260 may be performed at a temperature between about 75°C and about 500°C. In some embodiments, operation 260 may be performed for a period between about 1 minute and about 10 minutes. In some embodiments, operation 260 may be performed for a period of less than 1 minute. In some embodiments, operation 260 may be performed with a UV power percentage between 0% and about 90%. In some embodiments, operation 260 may be performed at a pressure between about 3 Torr and about 100 Torr. In some embodiments, the exposure to UV light in operation 260 may be performed in the presence of an oxygen-containingprecursor or an inert precursor. For example, the oxygen-containing precursor may be any oxygen-containing material such as, for example, molecular oxygen (O2) or ozone (03). The inert precursor may be any inert material such as, for example, argon, helium, or xenon.

[0074] FIG. 5 is a schematic block diagram of a method 500 for substrate processing, according to one or more embodiments. In some embodiments, the damaged low-kfilm may be processed and repaired using a source of direct plasma, for example, a direct capactively coupled plasma (CCP). In such an embodiment, the direct plasma is configured to generate a pulsed RF plasma in a processing region of a process chamber. As described above, pulsed RF plasma can be used to obtain high-precision plasma processing to control the dynamics of radical formation and the resulting ion radical ratio in the generated plasma. Accordingly, in some embodiments, the plasma source for generating the direct plasma may be a pulsed RF power source operable in a pulse mode. When in pulse mode, the plasma source may be pulsed at a pulse frequency between about 10 Hz to about 20 kHz, such as about 1 kHz. The plasma source may be operated at a duty cycle (e.g., the percentage of on time during the total of on time and off time in a given cycle) of between about 10% and about 90%, such as about 30%.

[0075] Method 500 may begin at operation 510 in which a substrate having a damaged low-k film is transferred into a plasma process chamber, such as a PECVD process chamber.

[0076] In operation 520, a precursor gas comprising a recovery precursor is flowed into the processing region of the process chamber. The precursor gas and recovery precursor may be the same as described above for method 200. Operation 520 includes exposing the damaged low-k film on the substrate to the precursor gas. In some embodiments, the precursor gas further contains one or more dilution gases, one or more carrier gases, and / or one or more purge gases. Suitable dilution gases, carrier gases, and / or purge gases such as helium (He), argon (Ar), xenon (Xe), hydrogen (H2), nitrogen (N2), ammonia (NH3), nitric oxide (NO), or any combination thereof, among others, may be co-flowed or otherwise supplied with the precursor gas into the processing region of the plasma process chamber.

[0077] In operation 530, RF power is applied to ignite the flowing precursor gas to generate a plasma in the processing region containing the substrate and damaged low-k film. In an embodiment, the plasma can be generated by any suitable technique known to the skilled artisan including, but not limited to, capactively coupled plasma, inductively coupled plasma and microwave plasma. In some embodiments, the plasma is a direct capacitively coupled plasma generated in the processing region over the substrate.

[0078] In an embodiment, the RF power applied in operation 530 for generating the direct plasma may be between about 50 Watts and about 2000 Watts, such as between about 100 Watts and about 1000 Watts, or between about 500 Watts and about 1500 Watts, such as about 800 Watts. The RF Power may be provided at a fixed or tunable frequency in a range from about 5 Hz to about 62 MHz, although other frequencies and powers may be provided as desired for particular applications. In certain embodiments, the RF power may be a high frequency RF power of approximately 13.56 MHz that is capable of producing either continuous or pulsed power, although other higher or lower frequencies and powers may be provided as desired for particular applications.

[0079] In some embodiments, operation 530 includes pulsing the RF Power to generate a pulsed RF plasma in the processing region. For example, in an embodiment, the RF power may be pulsed at a pulse frequency between about 10 Hz to about 20 kHz, such as about 1 kHz. The RF power may be operated at a duty cycle (e.g., the percentage of on time during the total of on time and off time in a given cycle) of between about 10% and about 90%, such as about 30%.

[0080] In operation 540, the damaged low-k film is exposed to the pulsed RF plasma generated in operation 530 to repair the damaged low-k film. Similar to method 200 described above, carbon from the recovery precursors used for generating the direct pulsing plasma are also deposited on and in the low-k film to replenish the carbon content of the damaged low-k film.

[0081] After the damaged low-k film is repaired in operation 530, a postprocessing treatment, for example, a UV curing process as described above in method 200 may be performed at an optional operation 550. Optional operation 550 may be the same as operation 260 discussed above for exposing the low-kfilm 310 to UV light.

[0082] In addition to replenishing loss carbon on the surface of the damaged low-k film 310 resulting in the depositing of the carbon layer over the low-k film 310, the methods 200 and 500 described herein also provide for replenishing carbon through a thickness of the low-k film 310. For example, method 200 provides for replenishing carbon content throughout a thickness of the low-k film 310 from a top surface of the low-k film 310 to a depth between about 5 A and about 20 A, such as about 15 A.

[0083] FIG. 6 is an XPS depth profile graph showing changes in the atomic concentrations of carbon in (1) pristine low-k film (e.g., as deposited before being damaged), (2) damaged low-k film, and (3) repaired low-k film after a damaged low-k film was repaired and carbon loss replenished by the techniques of the present disclosure. The XPS depth profile was obtained by etching each of the low-k films to depth of about 100 A. As shown in FIG. 6, prior to being etched, the atomic concentration of carbon for the repaired low-k film was the highest due to the additional carbon replenishment on the surface of the low-k film and lowest for the damaged low-k film due to the plasma damage. Up until about 50 seconds of etching, the atomic concentration of carbon in the repaired low-k film continued to be higher than the damaged low-k film. The higher carbon concentration in the etched portion of the repaired low-k film indicates that carbon from the precursor gas deposited by the methods described herein penetrated into the damaged low-k film and replenished loss carbon content throughout at least some of a thickness of the damaged low-k film. In the example shown, FIG. 6 indicates carbon was replenished in the repaired low-k film for a thickness of the repaired low-k film corresponding to about 50 seconds of etching (e.g., the point where the atomic concentration of carbon for the repaired low-k film and the damaged low-k film become approximately the same). .

[0084] While FIGS. 2 and 5 illustrate examples of methods for repairing damaged low-k film, it is to be noted that variations of methods 200 and 500 are contemplated. For example, it is contemplated that operation 240 may occur prior to operation 220. Additionally, it is contemplated that one or more of operations 220-214 may occur concurrently.

[0085] In certain embodiments, the techniques of the present disclosure may be applied in either single damascene or dual damascene processes. In either instances, after the low-k film is deposited and patterned, it may be advantageous to perform method 200 just prior to the removal of the etch stop layer to protect the sidewalls of the features in the patterned low-k film. For example, in the exemplary interconnection structure 301 shown in FIG. 3B in which an aluminum oxide layer (AIO) 312 and a SiOC layer 314 are formed between the low-k film 310 and the etch stop layer 330, the method 200 may be performed after each of the low-k film 310, the AIO layer 312, and the SiOC layer 314 are etched. Waiting to just prior to the removal of the etch stop layer 330 to repair the damage to low-k film 310 protects the low-k film 310 by minimizing the damage from further plasma operations after the low-k film 310 is repaired.

[0086] The following non-limiting examples are provided to further illustrate embodiments described herein. However, the examples are not intended to be all inclusive and are not intended to limit the scope of the embodiments described herein.Table 1

[0087] As shown in Table 1, both the k-value and carbon content % decreased after the pristine low-k film became damaged. However, in the repaired low-k film in which method 200 was performed utilizing 800 watt RF power pulsed at 30% duty cycle and 1000 Hz to repair the low-k film and replenish carbon loss, the k-value decreased and the carbon content % increased. As compared to a reference repaired low-k film repaired utilizing conventional methods, the k-value for the reference repaired low-k film also decreased, while the carbon content % remained low.

[0088] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0089] All numerical values within the detailed description herein are modified by “about” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0090] All documents described herein are incorporated by reference herein, including any priority documents and or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including” for purposes of United States law. Likewise whenever a composition, an element or a group of elements is preceded with the transitionalphrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0091] While the present disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims

What is claimed is:

1. A method for processing a substrate, comprising:generating plasma radicals in a remote plasma source;flowing a precursor gas comprising a recovery precursor into a processing region of a process chamber; andexposing the precursor gas and a low-kfilm on the substrate in the processing region to plasma radicals from the remote plasma source to decrease a k-value and increase a carbon content of the low-k film.

2. The method of claim 1 , wherein generating plasma radicals comprises flowing a radical forming gas in the remote plasma source and applying RF power to generate a remote plasma, wherein the remote plasma source is pulsed to tune and increase plasma radical formation in the remote plasma source.

3. The method of claim 2, wherein the radical forming gas comprises an inert gas.

4. The method of claim 2, wherein the remote plasma is generated by applying a RF power between about 50 Watts and about 1000 Watts.

5. The method of claim 2, wherein the remote plasma source is pulsed at a pulse frequency between about 10 Hz to about 20 kHz, and at a duty cycle between about 10% and about 90%.

6. The method of claim 1 , wherein the recovery precursor is flowed at a flow rate between about 100 mgm and about 2000 mgm.

7. The method of claim 1 , wherein the precursor gas further comprises a carrier gas comprising helium (He), argon (Ar), xenon (Xe), hydrogen (H2), nitrogen (N2), ammonia (NH3), nitric oxide (NO), or any combination thereof.

8. The method of claim 1 , wherein exposing the precursor gas and the low-k film to plasma radicals from the remote plasma source to increase the carbon content of the low-k film comprises replenishing the carbon content inat least a portion of a thickness of the low-k film and depositing a carbon layer on the low-k film.

9. The method of claim 1 , wherein exposing the precursor gas and the low-k film to plasma radicals from the remote plasma source increases the carbon content throughout the low-k film from a top surface of the low-k film to a depth between about 5 A and about 20 A within the low-k film.

10. The method of claim 1 , wherein the recovery precursor comprises a molecule selected from a group consisting of:, , and , wherein R is independently selected from methyl group (Me), ethyl group (Et), isopropyl group (iPr), tertiary butyl group (tBu), and hydrogen (H), and R’ is an alkane, alkene, or an alkyne.

11. The method of claim 1 , wherein the recovery precursor comprises a molecule selected from a group consisting of12. The method of claim 1 , wherein the recovery precursor comprises a molecule selected from a group consisting ofwherein R is independently selected from Me methyl group (Me), ethyl group (Et), isopropyl group (iPr), and tertiary butyl group (tBu), and R’ is an alkane, alkene, or an alkyne.

13. The method of claim 1 , wherein the recovery precursor comprises a molecule selected from a group consisting of, , and , wherein X is chlorine (Cl), bromine (Br), or iodine (I), and R’ is an alkane, alkene, or an alkyne.

14. The method of claim 1 , wherein the recovery precursor comprises a molecule with a formula:, wherein R’ is an alkane, alkene, or an alkyne.

15. The method of claim 1 , wherein the recovery precursor comprises a molecule with a formula:, wherein R is hydrogen, an alkane, an alkene, an alkyne, or an aryl, and R’ is hydrogen, an alkane, an alkene, an alkyne, or an aryl.

16. The method of claim 1 , wherein the recovery precursor comprises a molecule with a formula:R — CH — R”R’ , wherein R is hydrogen, an alkane, an alkene, an alkyne, or an aryl, R’ is hydrogen, an alkane, an alkene, an alkyne, or an aryl, and R” is hydrogen, an alkane, an alkene, an alkyne, or an aryl.

17. The method of claim 1 , wherein the recovery precursor comprises a molecule with a formula:, wherein R is hydrogen, an alkane, an alkene, an alkyne, or an aryl, R’ is hydrogen, an alkane, an alkene, an alkyne, or an aryl, R” is hydrogen, an alkane, an alkene, an alkyne, or an aryl, and, R” is hydrogen, an alkane, an alkene, an alkyne, or an aryl.

18. The method of claim 1 , wherein the recovery precursor comprises a molecule with a formula:, wherein R is hydrogen, an alkane, an alkene, an alkyne, or an aryl, and R’ is hydrogen, an alkane, an alkene, an alkyne, or an aryl.

19. A method for processing a substrate disposed in a processing region of a process chamber, comprising:exposing a low-k film on the substrate to a precursor gas comprising a recovery precursor;applying a RF power to the precursor gas and pulsing the RF Power to generate a pulsed plasma in the processing region, wherein the RF Power is pulsed at a pulse frequency between about 10 Hz to about 20 kHz, and at a duty cycle between about 10% and about 90%; andexposing the low-k film to the pulsed plasma to decrease a k-value and increase a carbon content of the low-k film.

20. A method for processing a substrate, comprising:disposing the substrate in a processing region of a process chamber, the substrate comprising a low-k film formed over an etch stop layer;patterning the substrate to form one or more features in the low-k film; generating plasma radicals in a remote plasma source;flowing a precursor gas comprising a recovery precursor into the processing region; andexposing the precursor gas and the low-k film on the substrate in the processing region to plasma radicals from the remote plasma source to decrease a k-value and increase a carbon content of the low-k film.

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