TWI469199B - Method for controlling dangling bonds in fluorocarbon films - Google Patents

Description

Control method of dangling bonds in fluorocarbon film [Reciprocal Reference of Related Applications]

The present application claims the benefit of U.S. Provisional Application Serial No. 61/454,320, filed on March 18, 2011, which is incorporated herein by reference.

The present invention relates generally to the deposition of dielectric films on substrates, and more particularly to methods of controlling dangling bonds in fluorocarbon films.

In a manufacturing process of an electronic device such as a semiconductor device, a liquid crystal display device, and an organic electroluminescent (EL) device, a film forming process is performed to form a conductive film or an insulating film on the surface of the substrate. A plasma film forming process for forming a thin film on a substrate using a plasma is commonly used in this film forming process, for example, to deposit interlayer dielectrics (ILDs) for integrated circuits.

Fluorocarbon (CF) films are prospective materials for use as low dielectric constant (low-k) ILDs and for other applications. When integrating a CF film with other materials, a problem often encountered is that the joint between the CF film and other materials is thermally deteriorated during subsequent processing. Further processing may include annealing of the copper wiring layers formed in the recessed features of the ILDs. It is considered that the thermal deterioration is caused by the decomposition reaction in the CF film due to the presence of dangling bonds in the CF film. The dangling bond contains an unsaturated carbon bond lacking a fluorine atom. Thermal degradation causes fluorine to diffuse and may cause a decrease in adhesion between the CF film and other materials in the integrated circuit. Ultimately, reduced adhesion can result in film erosion and film peeling that can be considered as foaming of the film on the substrate.

However, it is difficult to prepare a high quality CF film by plasma treatment, especially a high quality CF film having a low concentration of dangling bonds and good thermal stability. Increasing the thermal stability of the CF film prevents or reduces the diffusion of fluorine atoms and improves the adhesion between the CF film and other materials that contact the CF film. Attempts to reduce the total amount of fluorine on the surface of the CF film have included: performing heat treatment of the CF film before depositing other material layers on the CF film; or depositing on the CF film due to relatively good adhesion properties of the interfaces of the following two materials Titanium Genus. However, such attempts have not yet produced a manufacturable solution and new methods are needed to deposit CF films with low concentrations of dangling bonds and good thermal stability.

Embodiments of the present invention describe a deposition method for a CF film having a low concentration of dangling bonds and good thermal stability. According to an embodiment, the method comprises: providing a substrate on a substrate holder in a plasma processing chamber, the plasma processing chamber comprising a microwave antenna, a microwave power source for powering the microwave antenna, and a substrate holder An RF bias source for applying a radio frequency (RF) bias, and a DC voltage source for applying a direct current (DC) bias to the substrate holder; introducing a C _a F in the plasma processing chamber the first process gas a gas _b, wherein a and b are positive integers; RF bias by applying a first positive and the first DC bias to the substrate holder and forming a first process gas from the first plasma; and using The first plasma deposits a first fluorocarbon film on the substrate. The method further comprises: introducing _a second process gas containing C _a F _b gas into the plasma processing chamber, wherein a and b are positive integers; applying microwave power to the microwave antenna and applying a second RF bias and The second positive DC is biased to the substrate holder to form a second plasma from the second process gas; and the second fluorocarbon film is deposited on the first fluorocarbon film using the second plasma.

In accordance with another embodiment, the method includes providing a substrate on a substrate holder in a plasma processing chamber, the plasma processing chamber including a microwave antenna, a microwave power source for powering the microwave antenna, and a substrate a holder for applying a RF biased radio frequency (RF) bias source, and a direct current (DC) voltage source for applying a DC bias to the substrate holder; introducing a C _a F _b gas into the plasma processing chamber Process gas, wherein a and b are positive integers; plasma is formed from the process gas by applying an RF bias and a positive DC bias to the substrate holder; applying microwave power to the microwave antenna; and using the plasma on the substrate A fluorocarbon film is deposited wherein the applied microwave power is increased from a first microwave power level to a second microwave power level during deposition.

Deposition methods for CF films having low concentrations of dangling bonds and good thermal stability are described in various embodiments. Those who are familiar with the relevant technology will be aware that they may not have specific details. Various embodiments are implemented with one or more of the sections, or with other alternatives and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. The specific quantities, materials, and configurations are set forth to provide a thorough understanding of the invention. In addition, it is to be understood that the various embodiments are illustrated in the drawings

References to "an embodiment" throughout this specification mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but does not Appears in every embodiment. Thus, the appearance of the phrase "in an embodiment"

There is a general need in semiconductor fabrication for a new method for depositing CF films having low concentrations of dangling bonds and good thermal stability, which can be used in advanced semiconductor devices. The inventors have discovered that a high quality CF film having a low concentration of dangling bonds and good thermal stability can be deposited on a substrate by extracting negative fluoride ions (F ^- ) during deposition of the CF film by a self-depositing plasma. A processing gas derived from a fluorine-containing carbide gas by applying a large positive DC bias to a substrate holder configured to support a substrate. The negative fluoride ion extracted from the plasma reacts with the dangling bond of the unsaturated carbon in the CF film which is deficient in fluorine atoms. The reaction of the negative fluoride ion from the plasma with the dangling bond of the unsaturated carbon replaces the dangling bond of the unsaturated carbon in the CF film with a CF bond, which results in the deposited CF film having few dangling bonds and good thermal stability.

According to an embodiment of the present invention, a thick CF film can be formed on a substrate by first depositing a first high quality CF film having few dangling bonds on the substrate, and then depositing a second CF film on the first CF film. The inventors have discovered that the first CF film can provide a high quality deposition surface for depositing a second CF film on the first CF film. Without depositing the first high quality CF film, the second CF film (and the thick CF film of the combination of the first and second CF films in this manner) will have an unacceptably large number of dangling bonds and poor thermal stability. degree. The second CF film can be deposited at a higher deposition rate than the first CF film using different processing conditions during deposition of the first and second CF films. This allows for high substrate yields necessary in the fabrication of semiconductor devices. Can be used by applying a first RF bias and a first positive DC The first plasma formed by biasing the substrate holder configured to support the substrate deposits the first CF film on the substrate, wherein the first plasma can be applied to the microwave antenna in the plasma processing system without applying microwave power Formed under. The second CF film can be deposited at a high deposition rate by applying microwave power to the microwave antenna and applying a second RF bias and a second positive DC bias to the substrate holder.

1 is a flow diagram of forming a fluorocarbon film on a substrate in accordance with an embodiment of the present invention, and FIGS. 2A-2D schematically illustrate the formation of a fluorocarbon film on a substrate in accordance with an embodiment of the present invention. Referring to Figures 1 and 2A-2D, flowchart 100 includes, in step 102, providing a substrate 200 on a substrate holder in a plasma processing chamber. According to several embodiments, a first etch stop film 202 (such as SiO ₂ , SiN, or SiON) may be present on the substrate 200. According to other embodiments, the first etch stop film 202 may be omitted. The plasma processing chamber may include a microwave antenna, a microwave power source for powering the microwave antenna, a radio frequency (RF) power source for applying an RF bias to the substrate holder, and a DC bias for applying a substrate bias to the substrate holder Direct current (DC) voltage source. The microwave antenna may comprise a radial line slot antenna (RLSA) as shown schematically in Figures 3-5. The substrate 200 may be, for example, a semiconductor substrate such as a germanium substrate, a germanium substrate, a germanium substrate, a glass substrate, an LCD substrate, or a compound semiconductor substrate such as GaAs. The substrate can be of any size, such as a 200 mm wafer, a 300 mm wafer, a 450 mm wafer, or even a larger wafer or substrate.

In step 104, a first process gas comprising a C _a F _b gas is introduced into the plasma processing chamber, wherein a and b are positive integers. According to several embodiments, the C _a F _b gas may be selected from the group consisting of C ₄ F ₄ , C ₄ F ₆ , C ₆ F ₆ , C ₅ F ₈ , and other _Ca f _b gases. For example, the C _a F _b gas flow rate can be less than 500 sccm, less than 200 sccm, or less than 100 sccm. In several examples, the first process gas may further contain argon (Ar), (N _2), both N ₂ or Ar and nitrogen. The gas flow rate of the Ar and N ₂ gases may be less than 500 sccm, less than 200 sccm, or less than 100 sccm. For example, the gas pressure in the plasma processing chamber can be less than 100 mTorr, less than 50 mTorr, less than 30 mTorr, or less than 20 mTorr.

In step 106, the first plasma is formed from the first process gas by applying a first RF bias and a first positive DC bias to the substrate holder. For example, the first RF bias can be less than 100 W, less than 50 W, or less than 25 W. According to an embodiment, the first The plasma can be formed without applying microwave power to the microwave antenna. The first positive DC bias can be greater than 1.5 kV, such as 3 kV, 3.5 kV, or greater. In some examples, the first positive DC bias can be between 2 kV and 5 kV, between 2 kV and 3 kV, between 3 kV and 4 kV, or between 4 kV and 5 kV.

In step 108, the first fluorocarbon film 204 is deposited on the first etch stop film using the first plasma (Fig. 2B). According to several embodiments, the depositing of the first fluorocarbon film 204 may include maintaining the substrate holder at a temperature of, for example, greater than 330 ° C, greater than 340 ° C, greater than 350 ° C, or greater than 360 ° C. In some examples, the substrate temperature can be between 350 ° C and 380 ° C, or between 380 ° C and 400 ° C. In one example, the substrate holder can be maintained at a temperature of about 360 °C.

In step 110, a second process gas containing C _a F _b gas is introduced into the plasma processing chamber, wherein a and b are integers. According to several embodiments, the C _a F _b gas may be selected from the group consisting of C ₄ F ₄ , C ₄ F ₆ , C ₆ F ₆ , C ₅ F ₈ , and other _Ca f _b gases. The gas flow rate of the C _a F _b gas may be, for example, less than 500 sccm, less than 200 sccm, or less than 100 sccm. In some examples, the second process gas may further comprise argon (Ar), nitrogen (N ₂ ), or both Ar and N ₂ . The gas flow rate of the Ar and N ₂ gases may be less than 500 sccm, less than 200 sccm, or less than 100 sccm. The gas pressure in the plasma processing chamber can be, for example, less than 100 mTorr, less than 50 mTorr, less than 30 mTorr, or less than 20 mTorr.

In step 112, the second plasma is formed from the second process gas by applying plasma to form microwave power to the microwave antenna, and applying a second RF bias and a second positive DC bias to the substrate holder. The second RF bias can be the same or different than the first RF bias, such as less than 100 W, less than 50 W, or less than 25 W. The second positive DC bias can be lower than the first positive DC bias, such as less than 3 kV, less than 2.5 kV, less than 2 kV, or less than 1.5 kV. In some examples, the second positive DC bias can be between 1 kV and 2 kV, or between 2 kV and less than 3 kV. In an example, the first positive DC bias can be about 3 kV and the second positive DC bias can be about 1.5 kV.

In step 114, the second fluorocarbon film 206 is deposited on the first fluorocarbon film using a second plasma (Fig. 2C). According to several embodiments, the depositing of the second fluorocarbon film 206 may include maintaining the substrate holder at a temperature of, for example, greater than 300 °C, greater than 310 °C, greater than 320 °C, or greater than 330 °C. In several examples, the substrate The temperature can be between 300 ° C and 320 ° C, or between 320 ° C and 350 ° C. In one example, the substrate holder can be maintained at a temperature of about 330 °C. According to an embodiment, the deposition rate of the first fluorocarbon film 204 may be less than the deposition rate of the second fluorocarbon film 206.

Referring to FIG. 2D, a second etch stop film 208 (such as SiO ₂ , SiN, or SiON) may be deposited on the second fluorocarbon film 206. According to other embodiments, the second etch stop film 208 may be omitted.

According to several embodiments, the first positive DC bias may be greater than the second positive DC bias. In several examples, the first positive DC bias can be equal to or greater than 3 kV. In an example, the second positive DC bias can be about 1.5 kV.

According to several embodiments, the first fluorocarbon film 204 may be deposited at a first substrate holder temperature, and the second fluorocarbon film may be deposited at a second substrate holder temperature lower than the first substrate holder temperature. 206.

According to several embodiments, the thickness of the first fluorocarbon film 204 may be less than the thickness of the second fluorocarbon film 206. In one example, the first fluorocarbon film may have a thickness of 20 nm or less, such as between 5 nm and 10 nm, or between 10 nm and 20 nm. In one example, the second fluorocarbon film has a thickness of 30 nm or greater, such as between 30 nm and 200 nm, between 30 nm and 100 nm, or between 100 nm and 200 nm.

3 is a schematic illustration of a plasma processing system including a RLSA plasma source for depositing a fluorocarbon film on a substrate in accordance with an embodiment of the present invention. The plasma produced in the plasma processing system 500 is characterized by a low electron temperature and a high plasma density. Plasma processing system 500 may be for example the power of families from Japan Tokyo Akasaka creator TRIAS ^TM SPA Processing System Incorporated. The plasma processing system 500 includes a plasma processing chamber 550 having an opening 551 that is larger than the substrate 558 in an upper portion of the plasma processing chamber 550. A cylindrical dielectric top plate 554 made of quartz, aluminum nitride, or aluminum oxide is provided to cover the opening portion 551.

Gas line 572 is located in the sidewall of the upper portion of plasma processing chamber 550 below top plate 554. In one example, the number of gas lines 572 can be 16 (only two of which are shown in Figure 3). Alternatively, a different number of gas lines 572 can be used. The gas line 572 can be circumferentially arranged in the plasma processing chamber 550, but this is not required by the present invention. The process gas can be supplied uniformly and consistently from the gas line 572 to the plasma region 559 in the plasma processing chamber 550. The process gas may contain _a C _a F _b gas which may be selected from the group consisting of C ₄ F ₄ , C ₄ F ₆ , C ₆ F ₆ and C ₅ F ₈ , and other C _a F _b gases. The gas flow rate of the C _a F _b gas may be less than 500 sccm, less than 200 sccm, or less than 100 sccm. The process gas may further contain argon (Ar), nitrogen (N ₂ ), or both Ar and N ₂ . The gas flow rate of the Ar and N ₂ gases may be less than 500 sccm, less than 200 sccm, or less than 100 sccm. The gas pressure in the plasma processing chamber can be, for example, less than 100 mTorr, less than 50 mTorr, less than 30 mTorr, or less than 20 mTorr.

In the plasma processing system 500, microwave power is provided to the plasma processing chamber 550 through the top plate 554 via a slot antenna 560 having a plurality of slots 560A. The slot antenna 560 faces the substrate 558 to be processed, and the slot antenna 560 can be made of a metal plate such as copper. In order to supply microwave power to the slot antenna 560, the waveguide 563 is disposed on the top plate 554, wherein the waveguide 563 is coupled to a microwave power source 561 for generating microwaves having a frequency of, for example, about 2.45 GHz. The waveguide 563 includes a planar circular waveguide 563A connected to the lower end of the slot antenna 560, a circular waveguide 563B connected to the upper surface side of the circular waveguide 563A, and a coaxial connected to the upper surface side of the circular waveguide 563B. Waveguide converter 563C. Furthermore, the rectangular waveguide 563D is connected to the side of the coaxial waveguide converter 563C and the microwave power source 561.

Inside the circular waveguide 563B, the axial portion 562 of the conductive material is coaxially disposed such that one end of the axial portion 562 is coupled to the center (or near center) portion of the upper surface of the slot antenna 560, and the axial portion 562 The other end is connected to the upper surface of the circular waveguide 563B to form a coaxial structure. Therefore, the circular waveguide 563B is constructed to operate as a coaxial waveguide. The microwave power can be, for example, between about 0.5 W/cm ² and about 4 W/cm ² . Alternatively, the microwave power can be between about 0.5 W/cm ² and about 3 W/cm ² . The microwave radiation may contain a microwave frequency of from about 300 MHz to about 10 GHz, such as about 2.45 GHz, and the plasma may contain an electron temperature of less than or equal to 5 eV, including 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5. Or 5 eV, or any combination thereof. In other examples, the electron temperature can be below 5 eV, below 4.5 eV, below 4 eV, or even below 3.5 eV. In some examples, the electron temperature can be between 3.0 and 3.5 eV, between 3.5 eV and 4.0 eV, or between 4.0 and 4.5 eV. The plasma may have a density of from about 1 x 10 ¹¹ /cm ³ to about 1 x 10 ¹³ /cm ³ or higher.

Additionally, in the plasma processing chamber 550, a substrate holder 552 is disposed opposite the top plate 554 for supporting and heating the substrate 558 (eg, a wafer). The substrate holder 552 contains a heater 557 to heat the substrate 558, wherein the heater 557 can be a resistive heater. Alternatively, heater 557 can be a lamp heater or any other form of heater. Further, the plasma processing chamber 550 includes a discharge line 553 that is coupled to the bottom of the plasma processing chamber 550 and to a vacuum pump 555.

The plasma processing system 500 further includes a substrate biasing system 556 configured to bias the substrate holder 552 and the substrate 558 to generate plasma and/or control the energy of ions that are drawn to the substrate 558. Substrate biasing system 556 includes a substrate power source for coupling power to substrate holder 552. The substrate power supply contains an RF generator and an impedance matching network. The substrate power supply is configured to couple power to the substrate holder 552 by supplying electrode energy in the substrate holder 552. Typical frequencies for RF bias can range from about 0.1 MHz to about 100 MHz and can be 13.56 MHz. In several examples, the RF bias can be less than 1 MHz, such as less than 0.8 MHz, less than 0.6 MHz, less than 0.4 MHz, or even less than 0.2 MHz. In one example, the RF bias can be about 0.4 MHz. Optionally, the RF power is applied to the electrodes at a plurality of frequencies. The substrate biasing system 556 is configured to supply RF bias power between 0 W and 100 W, between 100 W and 200 W, between 200 W and 300 W, 300 W and 400 W. Between, or between 400 W and 500 W. In several examples, the RF bias power can be, for example, less than 100 W, less than 50 W, or less than 25 W. RF biasing systems for plasma processing are well known to those skilled in the art. Further, substrate biasing system 556 includes a DC voltage generator that can supply a DC bias between -5 kV and +5 kV to substrate holder 552.

Substrate biasing system 556 is further configured to selectively provide pulses of RF bias power. The pulse frequency can be greater than 1 Hz, such as 2 Hz, 4 Hz, 6 Hz, 8 Hz, 10 Hz, 20 Hz, 30 Hz, 50 Hz, or greater. It should be noted that those skilled in the art will appreciate that the power level of the substrate biasing system 556 is related to the size of the substrate being processed. For example, a 300 mm Si wafer requires more work than a 200 mm wafer during processing. Rate consumption.

Still referring to FIG. 3, controller 599 is configured to control plasma processing system 500. Controller 599 can include a microprocessor, memory, and digital I/O ports capable of generating a control voltage sufficient to communicate and initiate input to plasma processing system 500 and monitor output from plasma processing system 500. Furthermore, the controller 599 is coupled to the plasma processing chamber 550, the vacuum pump 555, the heater 557, the substrate biasing system 556, and the microwave power source 561 to exchange information. The program stored in the memory is used to control the components of the plasma processing system 500 described above in accordance with the stored process recipe. An example of controller 599 is a UNIX based workstation. Alternatively, the controller 599 can be implemented as a general purpose computer, a digital signal processing system, or the like.

The processing conditions for depositing the fluorocarbon film in the plasma processing system 500 can include a substrate temperature between about 300 ° C and about 500 ° C, such as between about 300 ° C and about 400 ° C. For example, the pressure in the plasma processing chamber 550 can be maintained, for example, less than 100 mTorr, less than 50 mTorr, less than 30 mTorr, or less than 20 mTorr.

4 is a schematic diagram of a plasma processing system including a radial line slot antenna (RLSA) plasma source for depositing fluorocarbon on a substrate in accordance with another embodiment of the present invention. membrane. As shown in FIG. 4, the plasma processing system 10 includes a plasma processing chamber 20 (vacuum chamber), an antenna unit 50, and a substrate holder 21. The inside of the plasma processing chamber 20 is roughly divided into a plasma generating region R1 located below the plasma gas supply unit 30 and a plasma diffusion region R2 above the substrate holder 21. The plasma generated in the plasma generating region R1 may have an electron temperature of several electron volts (eV). When the plasma is diffused into the plasma diffusion region R2 in which the film formation process is performed, the electron temperature of the plasma close to the substrate holder 21 can be lowered to a value lower than about 2 eV. The substrate holder 21 is centrally located on the bottom of the plasma processing chamber 20 and serves as a substrate holder for the support substrate W. Inside the substrate holder 21, an insulating member 21a, a cooling jacket 21b, and a temperature control unit (not shown) for controlling the temperature of the substrate are provided.

The top of the plasma processing chamber 20 is of the open end type. The plasma gas supply unit 30 is disposed opposite the substrate holder 21 and attached to the top of the plasma processing chamber 20 via a sealing member (not shown) such as an O-ring. Can also be used as a plasma gas for dielectric windows The supply unit 30 may be made of a material such as alumina or quartz and has a flat surface. The plurality of gas supply holes 31 are provided on the opposite side of the substrate holder 21 and the plane of the plasma gas supply unit 30. The plurality of gas supply holes 31 communicate with the plasma gas supply port 33 via the gas flow path 32. The plasma gas supply source 34 supplies a plasma gas such as argon (Ar) gas or other inert gas into the plasma gas supply port 33. Then, the plasma gas is uniformly supplied into the plasma generation region R1 via the plurality of gas supply holes 31.

The plasma processing system 10 further includes a process gas supply unit 40 that is coupled in the plasma processing chamber 20 between the plasma generation region R1 and the plasma diffusion region R2. The process gas supply unit 40 may be made of a conductive material such as an aluminum alloy or stainless steel containing magnesium (Mg). Similar to the plasma gas supply unit 30, a plurality of gas supply holes 41 are provided on the plane of the process gas supply unit 40. The plane of the process gas supply unit 40 is disposed opposite the substrate holder 21.

The plasma processing chamber 20 further includes a discharge line 26 connected to the bottom of the plasma processing chamber 20, a vacuum line 27 connecting the discharge line 26 to the pressure controller valve 28 and the vacuum pump 29. Pressure controller valve 28 may be used to achieve a desired gas pressure in plasma processing chamber 20.

A top view of the process gas supply unit 40 is shown in FIG. As shown in the figure, a lattice flow passage 42 is formed in the process gas supply unit 40. The lattice air flow passage 42 communicates with the upper end of the plurality of gas supply holes 41 formed in the vertical direction. The lower portion of the plurality of gas supply holes 41 is an opening facing the substrate holder 21. The plurality of gas supply holes 41 communicate with the process gas supply port 43 via the lattice gas flow path 42.

Further, a plurality of openings 44 are formed in the process gas supply unit 40 such that the plurality of openings 44 pass through the process gas supply unit 40 in the vertical direction. The plurality of openings 44 introduce a plasma gas such as argon (Ar) gas, helium (He) gas, or other inert gas into the plasma diffusion region R2 above the substrate holder 21. As shown in FIG. 5, a plurality of openings 44 are formed between adjacent airflow passages 42. The process gas may be supplied to the process gas supply port 43 from separate three process gas supply sources 45-47. The process gas supply sources 45-47 can supply C ₅ F ₈ gas (or generally C _a F _b gas), Ar, and N ₂ .

The process gas flows through the lattice gas flow passage 42 and passes through the plurality of gas supply holes 41 It is uniformly supplied into the plasma diffusion region R2. The plasma processing system 10 further includes four valves (V1-V4) and four mass flow controllers (MFC1-MFC4) for controlling the supply of process gases.

The external microwave generator 55 supplies microwaves of a predetermined frequency of 2.45 GHz to the antenna unit 50 via the coaxial waveguide 54. The coaxial waveguide 54 can include an inner conductor 54B and an outer conductor 54A. The microwave from the microwave generator 55 generates an electric field directly under the plasma gas supply unit 30 in the plasma generating region R1, thereby causing the processing gas in the plasma processing chamber 20 to be excited.

FIG. 6 shows a partial cross-sectional view of the antenna unit 50. As shown in this figure, the antenna unit 50 can include a planar antenna body 51, a radiation slot plate 52, and a dielectric plate 53 to shorten the microwave wavelength. The planar antenna body 51 can have a circular shape with an open end type bottom surface. The planar antenna body 51 and the radiation slot plate 52 may be made of a conductive material.

A plurality of slots 56 are provided on the radiation slot plate 52 to create a circularly polarized wave. The plurality of slots 56 are arranged in a substantially T-shaped form with small gaps between the slots. The plurality of slots 56 are arranged in a circumferentially concentric circular pattern or a spiral pattern. Since the slots 56a and 56b are perpendicular to each other, a circularly polarized wave system having two orthogonal polarization components is emitted from the radiation slot plate 52 as a plane wave.

The dielectric plate 53 may be made of a low loss dielectric material such as aluminum oxide (Al ₂ O ₃ ) or tantalum nitride (Si ₃ N ₄ ), which is located between the radiation slot plate 52 and the planar antenna body 51. . The radiation slot plate 52 can be mounted to the plasma processing chamber 20 using a sealing member (not shown) such that the radiation slot plate 52 is in intimate contact with the cover plate 23. The cover plate 23 is located on the upper surface of the plasma gas supply unit 30, and is formed of a microwave transporting dielectric material such as alumina (Al ₂ O ₃ ).

The external high frequency power supply source 22 is electrically connected to the substrate holder 21 via the matching network 25. The external high frequency power supply 22 generates an RF bias power of a predetermined frequency, for example 13.56 MHz, for controlling the energy of ions drawn into the plasma of the substrate W. The power supply 22 is further configured to selectively provide pulses of RF bias power. The pulse frequency can be greater than 1 Hz, such as 2 Hz, 4 Hz, 6 Hz, 8 Hz, 10 Hz, 20 Hz, 30 Hz, 50 Hz, or greater. The power supply source 22 is configured to supply between 0 W and 100 W, between 100 W and 200 W, between 200 W and 300 W, 300 RF bias power between W and 400 W, or between 400 W and 500 W. Those skilled in the art will recognize that the power level of the power supply source 22 is related to the size of the substrate being processed. For example, a 300 mm Si wafer requires more power consumption than a 200 mm wafer during processing. The plasma processing system 10 further includes a DC voltage generator 35 that can supply a DC voltage bias between -5 kV and 5 kV to the substrate holder 21.

During the deposition of the CF film, a plasma gas such as argon (Ar) gas may be introduced into the plasma processing chamber 20 using the plasma gas supply unit 30. Alternatively, the process gas supply unit 40 can be used to introduce process gases into the plasma processing chamber 20. Although not shown in FIG. 4, one or more of C ₅ F ₈ (or generally C _a F _b ), Ar, and N ₂ may also be introduced into the plasma processing chamber 20 using the plasma gas supply unit 30. in.

According to several embodiments, the CF film can be deposited in a continuous process in which one or more of the microwave power level, the substrate holder temperature, and the positive DC bias are changed during film deposition. This is shown schematically in Figures 7-9.

Figures 7A-7C schematically show changes in microwave power level during deposition of a fluorocarbon film. Film deposition begins at t0. Figure 7A shows a microwave power level profile 700 in which a first microwave power level P1 is applied between times t0 and t. At time t, the microwave power level rises from P1 to the second microwave power level P2, and the film deposition continues at the second microwave power level P2. FIG. 7B shows that in trace 710, the microwave power level is monotonically increased from the first microwave power level P1 to the second microwave power level P2 during film deposition. Figure 7C shows that in trace 720, the microwave power level at time t is monotonically increased from the first microwave power level P1 to the second microwave power level P2. In several instances, P1 can be zero, and thus no microwave power is applied during deposition of the first fluorocarbon film between times t0 and t. In several examples, the power level P2 can be greater than 1 kW, such as about 1.35 kW.

Figures 8A-8C schematically show changes in substrate holder temperature during fluorocarbon film deposition. Film deposition begins at t0. Figure 8A shows a substrate holder temperature profile 800 in which the first substrate holder temperature T1 is used between times t0 and t. At time t, the substrate holder temperature drops from T1 to the second substrate holder temperature T2, and the film deposition continues at the second substrate holder temperature T2. Figure 8B shows the first substrate holder in the trace 810 that causes the substrate holder temperature to be from t0 during film deposition. The holder temperature T1 monotonically decreases to the second substrate holder temperature T2. Figure 8C shows that in trace 820, the substrate holder temperature for time t is monotonically decreasing from the first substrate holder temperature T1 to the second substrate holder temperature T2. In several examples, T1 can be about 360 °C and T2 can be about 330 °C. According to several embodiments, a first fluorocarbon film may be deposited between times t0 and t, and a second fluorocarbon film is deposited on the first fluorocarbon film at a time greater than t.

Figures 9A-9C schematically show changes in the positive DC bias applied to the substrate holder during deposition of the fluorocarbon film. Film deposition begins at t0. Figure 9A shows a DC bias curve 900 in which a positive DC bias DC1 is used between times t0 and t. At time t, the DC bias drops from DC1 to a second positive DC bias DC2 and the film deposition continues at the second DC bias DC2. FIG. 9B shows that in trace 910, the first positive DC bias DC1 when the DC bias is applied from t0 is monotonically reduced to the second positive DC bias DC2 during thin film deposition. 9C shows that in trace 920, the DC bias of time t is monotonically decreasing from the first positive DC bias DC1 to the second positive DC bias DC2. In an example, DC1 can be about 3 kV and DC2 can be about 1.5 kV. According to several embodiments, a first fluorocarbon film may be deposited between times t0 and t, and a second fluorocarbon film is deposited on the first fluorocarbon film at a time greater than t.

In accordance with embodiments of the present invention, any changes in the different microwave power levels, substrate holder temperatures, and DC biases that are schematically illustrated in Figures 7-9 can be used during CF film deposition.

In accordance with an embodiment of the present invention, a method for forming a semiconductor device is provided. The method includes providing a substrate on a substrate holder in a plasma processing chamber, the plasma processing chamber including a microwave antenna, a microwave power source for powering the microwave antenna, and applying a radio frequency to the substrate holder ( RF biased RF bias source, and a DC voltage source for applying a direct current (DC) bias to the substrate holder. The method further includes introducing _a first process gas comprising a C _a F _b gas into the plasma processing chamber. In an example, the first process gas can comprise C ₅ F ₈ , Ar, and N ₂ . Thereafter, the first plasma is formed from the first processing gas in the plasma processing system by applying the first RF bias and the first positive DC bias to the substrate holder, and is exposed to the first plasma. A substrate holder temperature deposits a first fluorocarbon film on the substrate. In one example, the first substrate holder temperature can be about 360 ° C, the first RF bias can be about 25 W, and the first positive DC bias can be about 3 kV. In an example, the first plasma can be formed without applying microwave power to the microwave antenna.

Thereafter, the method further comprises: introducing _a second process gas containing C _a F _b gas into the plasma processing chamber. In an example, the second process gas can comprise C ₅ F ₈ , Ar, and N ₂ . The second plasma is formed from the second process gas by applying microwave power to the microwave antenna and applying a second RF bias and a second positive DC bias to the substrate holder, wherein the second plasma is exposed The second substrate holder temperature deposits a second fluorocarbon film on the first fluorocarbon film. In one example, the second substrate holder temperature can be about 330 ° C, the microwave power can be about 1.35 kW, the second RF bias can be about 25 W, and the second positive DC bias can be about 1.5 kV. Further processing conditions may include a gas pressure of about 23 mTorr, an Ar gas stream of about 100 sccm, and a N ₂ gas stream of about 20 sccm.

The CF film deposited under different processing conditions was evaluated by performing post-deposition annealing and monitoring any blistering or peeling of the film. The test structure contained CF deposited under different processing conditions. The test structure comprises (in the order of deposition on the Si wafer): a first SiN etch stop film / a first CF film / a second CF film / a second SiN etch stop film / SiC cap layer. a first CF film deposited using a first substrate holder temperature of 360 ° C and a first positive DC bias of 3 kV, and a second substrate holder temperature of 330 ° C using a second substrate holder temperature of 330 ° C The test structure of the second CF film directly formed on the first CF film with a bias voltage and a microwave power of 1.35 kW did not show signs of blistering or peeling. This confirms that the test structure has a low concentration of dangling bonds in the first and second CF films and thus good thermal stability.

In contrast, the test structure containing the first CF film deposited at a substrate holder temperature of 300 ° C or 330 ° C and a first bias power of 1.5 kV or minus 3 kV did not pass the annealing test. Further, the test structure containing the first CF film deposited at a substrate holder temperature of 300 ° C or 330 ° C and a first bias power of 3 kV did not pass the annealing test. The second CF film was deposited using a second substrate holder temperature of 330 ° C and a second bias power of 3 kV. Further analysis using the test structure of Electro Energy Loss Spectroscopy (EELS) shows Improved C-C bonding and increased C-F bonding in the test structure over-annealed. The EELS analysis also shows an improved interface between the first SiN etch stop film and the first CF film in the test structure that was annealed.

A plurality of embodiments of using a microwave plasma source to form a fluorocarbon of a semiconductor device have been described herein. The foregoing description of the embodiments of the invention has been presented for purposes of illustration The invention is not intended to be exhaustive or to limit the invention to the precise form disclosed. The content of the description and the following claims are intended to be illustrative only and not to be construed as limiting. For example, the term "on" as used herein (including in the scope of the claims) does not require that the film "on" the substrate be directly on the substrate and next to the substrate; there may be a second film or other structure between the film and the substrate. .

Those skilled in the relevant art will recognize that many modifications and variations are possible in light of the above teachings. Various equivalent combinations and substitutions of the various components shown in the drawings will be apparent to those skilled in the art. Therefore, the scope of the invention is not intended to be

10‧‧‧Plastic Processing System

20‧‧‧The plasma processing chamber

21‧‧‧Substrate holder

21a‧‧‧Insulating components

21b‧‧‧Cooling sleeve

22‧‧‧Power supply

23‧‧‧ Cover

25‧‧‧matching network

26‧‧‧Drainage line

27‧‧‧vacuum pipeline

28‧‧‧pressure controller valve

29‧‧‧Vacuum pump

30‧‧‧ Plasma Gas Supply Unit

31‧‧‧ gas supply hole

32‧‧‧Air passage

33‧‧‧ Plasma gas supply埠

34‧‧‧ Plasma gas supply

35‧‧‧DC voltage generator

40‧‧‧Processing gas supply unit

41‧‧‧ gas supply hole

42‧‧‧Air passage

43‧‧‧Processing gas supply埠

44‧‧‧ plural openings

45‧‧‧Processing gas supply

46‧‧‧Processing gas supply

47‧‧‧Processing gas supply

50‧‧‧Antenna unit

51‧‧‧ planar antenna body

52‧‧‧radiation slot plate

53‧‧‧ dielectric board

54‧‧‧Coaxial waveguide

54A‧‧‧Outer conductor

54B‧‧‧ Inner conductor

55‧‧‧Microwave generator

56‧‧‧Multiple slots

56a‧‧‧Slot

56b‧‧‧Slot

100‧‧‧ Flowchart

102‧‧‧Steps

104‧‧‧Steps

106‧‧‧Steps

108‧‧‧Steps

110‧‧‧Steps

112‧‧‧Steps

114‧‧‧Steps

200‧‧‧Substrate

202‧‧‧First etching stop film

204‧‧‧First fluorocarbon film

206‧‧‧Second fluorocarbon film

208‧‧‧Second etching stop film

500‧‧‧Plastic Processing System

550‧‧‧plasma processing chamber

551‧‧‧ openings

552‧‧‧Substrate holder

553‧‧‧Drainage line

554‧‧‧ top board

555‧‧‧vacuum pump

556‧‧‧Substrate bias system

557‧‧‧heater

558‧‧‧Substrate

559‧‧‧The plasma area

560‧‧‧Slot antenna

560A‧‧‧Slot

561‧‧‧Microwave power supply

562‧‧‧Axial section

563‧‧‧Band

563A‧‧‧Circular waveguide

563B‧‧‧Circular waveguide

563C‧‧‧Coaxial Waveguide Converter

563D‧‧‧Rectangular Waveguide

572‧‧‧ gas pipeline

599‧‧‧ Controller

700‧‧‧ Curve

710‧‧‧ trace

720‧‧‧ traces

800‧‧‧ curve

810‧‧‧ trace

820‧‧‧ trace

900‧‧‧ Curve

910‧‧‧ trace

920‧‧‧ traces

MFC1‧‧‧Quality Flow Controller

MFC2‧‧‧Quality Flow Controller

MFC3‧‧‧Quality Flow Controller

MFC4‧‧‧Quality Flow Controller

R1‧‧‧plasma generation area

R2‧‧‧plasma diffusion area

V1‧‧‧ valve

V2‧‧‧ valve

V3‧‧‧ valve

V4‧‧‧ valve

W‧‧‧Substrate

1 is a flow chart for forming a fluorocarbon film on a substrate according to an embodiment of the present invention; and FIGS. 2A-2D schematically show the formation of a fluorocarbon film on a substrate according to an embodiment of the present invention; A schematic diagram of a plasma processing system according to an embodiment of the present invention, the plasma processing system comprising a radial line slot antenna (RLSA) plasma source for depositing a fluorocarbon film on the substrate; A schematic diagram of another plasma processing system according to an embodiment of the present invention, the plasma processing system comprising a radial line slot antenna (RLSA) plasma source for depositing fluorocarbon on the substrate; FIG. 6 is a partial cross-sectional view showing the antenna portion of the plasma processing system of FIG. 4; and FIGS. 7A-7C, FIGS. 8A-8C, and 9A-9C. Illustratively showing according to the invention Several embodiments show changes in microwave power level, substrate holder temperature, and DC bias during fluorocarbon film deposition.

100‧‧‧ Flowchart

102‧‧‧Steps

104‧‧‧Steps

106‧‧‧Steps

108‧‧‧Steps

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114‧‧‧Steps

Claims (20)

A method of forming a semiconductor device, comprising: providing a substrate on a substrate holder in a plasma processing chamber, the plasma processing chamber comprising a microwave antenna, a microwave power source for supplying power to the microwave antenna, The substrate holder applies an RF bias source of a radio frequency (RF) bias, and a DC voltage source for applying a direct current (DC) bias to the substrate holder; Introducing _a first process gas containing C _a F _b gas in the chamber, wherein a and b are positive integers; from the first by applying a first RF bias and a first positive DC bias to the substrate holder Processing gas to form a first plasma; depositing a first fluorocarbon film on the substrate by using the first plasma; introducing _a second processing gas containing C _a F _b gas into the plasma processing chamber, wherein b is a positive integer; forming a second plasma from the second process gas by applying microwave power to the microwave antenna, and applying a second RF bias and a second positive DC bias to the substrate holder; and utilizing The second plasma deposits a second fluorocarbon film on the first fluorocarbon film. The method of forming a semiconductor device according to claim 1, wherein the first plasma is formed without applying microwave power to the microwave antenna. A method of forming a semiconductor device according to claim 1, wherein the first positive DC bias is greater than the second positive DC bias. A method of forming a semiconductor device according to claim 3, wherein the first positive DC bias is equal to or greater than 3 kV. The method of forming a semiconductor device according to claim 1, wherein the first fluorocarbon film is deposited at a temperature of the first substrate holder, and the second fluorocarbon film is lower than the first substrate holder The temperature of the second substrate holder is deposited. The method of forming a semiconductor device according to claim 1, wherein the microwave antenna comprises a radial line slot antenna (RLSA). The method of forming a semiconductor device according to claim 1, wherein the C _a F _b gas system is selected from the group consisting of C ₄ F ₄ , C ₄ F ₆ , C ₆ F ₆ and C ₅ F ₈ . The method of forming a semiconductor device according to claim 1, wherein the first and second process gases contain the same C _a F _b gas. The method of forming a semiconductor device according to claim 1, wherein the first and second processing gases further comprise argon (Ar), nitrogen (N ₂ ), or both Ar and N ₂ . The method of forming a semiconductor device according to claim 1, wherein the thickness of the first fluorocarbon film is smaller than the thickness of the second fluorocarbon film. The method of forming a semiconductor device according to claim 1, wherein the first fluorocarbon film has a thickness of 20 nm or less, and wherein the second fluorocarbon film has a thickness of 30 nm or more. The method of forming a semiconductor device according to claim 1, wherein a deposition rate of the first fluorocarbon film is lower than a deposition rate of the second fluorocarbon film. A method of forming a semiconductor device, comprising: providing a substrate on a substrate holder in a plasma processing chamber, the plasma processing chamber comprising a microwave antenna, a microwave power source for supplying power to the microwave antenna, The substrate holder applies a radio frequency (RF) biased RF bias source, and a DC voltage source for applying a direct current (DC) bias to the substrate holder; introducing a C in the plasma processing chamber _a processing gas of F _b gas, wherein a and b are positive integers; forming a plasma from the processing gas by applying an RF bias and a positive DC bias to the substrate holder; applying microwave power to the microwave antenna; And depositing a fluorocarbon film on the substrate using the plasma, wherein the applied microwave power is raised from the first microwave power level to the second microwave power level during the deposition. The method of forming a semiconductor device according to Item 13, wherein the plasma is formed without applying microwave power to the microwave antenna. The method for forming a semiconductor device of claim 13, further comprising: reducing the positive DC bias from the first positive DC bias to the second positive DC bias during the depositing Pressure. The method for forming a semiconductor device according to claim 13 , further comprising: reducing a temperature of the substrate holder from a first substrate holder temperature to a second substrate holder temperature during the deposition. The method of forming a semiconductor device according to claim 13, wherein the microwave antenna comprises a radial line slot antenna (RLSA). The method of forming a semiconductor device according to claim 13, wherein the C _a F _b gas system is selected from the group consisting of C ₄ F ₄ , C ₄ F ₆ , C ₆ F ₆ and C ₅ F ₈ . The method of forming a semiconductor device according to Item 13, wherein the processing gas further contains argon (Ar), nitrogen (N ₂ ), or both Ar and N ₂ . The method of forming a semiconductor device according to Item 13, wherein the deposition rate of the fluorocarbon film is increased during the deposition.