Pulsed plasma (DC / RF) deposition of high quality c film for patterning

Abstract

To provide a method for depositing an amorphous carbon layer onto a substrate, including over previously formed layers on the substrate, using a plasma-enhanced chemical vapor deposition (PECVD) process, and forming a hardmask layer.SOLUTION: A method utilizes a combination of RF AC power and pulsed DC power to create a plasma which deposits an amorphous carbon layer with a high ratio of sp3 (diamond-like) carbon to sp2 (graphite-like) carbon. The method also provides for lower processing pressures, lower processing temperatures, and higher processing powers, and each of which, alone or in combination, may further increase the relative fraction of sp3 carbon in the deposited amorphous carbon layer. As a result of the higher sp3 carbon fraction, the method can provide amorphous carbon layers having improved density, rigidity, etch selectivity, and film stress as compared to amorphous carbon layers deposited by conventional methods.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Embodiments of the present disclosure relate to methods for depositing an amorphous carbon layer on a substrate, including over a layer previously formed on the substrate, using a plasma enhanced chemical vapor deposition (PECVD) process. [Background technology]

[0002] Carbon hard masks formed from amorphous carbon are used in the fabrication of semiconductor devices as etch masks for forming high-aspect-ratio openings (e.g., height-to-width ratios of 2:1 or greater) in substrate surfaces or material surface layers. Processing issues associated with forming high-aspect-ratio openings, including clogging, hole-shape distortion, pattern deformation, top critical dimension blowup, line bending, and profile bowing, are generally the result of undesirable material properties of conventionally deposited carbon hard masks. For example, carbon hard masks with lower material density and / or lower material stiffness (i.e., Young's modulus) are known to increase deformation of high-aspect-ratio openings compared to hard mask materials with higher density or stiffness.

[0003] Similarly, reduced etch selectivity between hard mask materials and substrate materials can cause increased slit pattern deformation and line bending compared to hard masks exhibiting higher etch selectivity. Similar problems can be caused by high film stress (compressive or tensile). Furthermore, as critical dimensions (CDs) shrink and the size of high-aspect-ratio openings increases, the thickness of conventional deposited carbon hard masks used to form high-aspect-ratio openings also increases. Unfortunately, hard masks with lower transparency due to one or both of a low optical K and increased thickness can cause mismatches in subsequent photolithography processes. Furthermore, processes with lower etch selectivity between hard mask materials and the underlying substrate material often rely on relatively thicker hard masks, which increases processing time and costs.

[0004] Therefore, what is needed in the art are improved hardmasks and methods of forming the improved hardmasks. Summary of the Invention

[0005] In one embodiment, a method for processing a substrate is provided. The method includes positioning the substrate on a substrate support disposed within a processing volume of a processing chamber. The method further includes flowing a process gas, including a hydrocarbon gas and a diluent gas, into the processing volume. The method further includes maintaining the processing volume at a pressure less than about 100 mTorr. The method further includes forming a plasma of the process gas by applying a first power to a first electrode of the processing chamber and applying a second power, the second power being pulsed DC power, to a second electrode of the processing chamber. The method further includes maintaining the substrate support at a temperature less than about 350°C. The method further includes exposing a surface of the substrate to the plasma. The method further includes depositing an amorphous carbon layer on the surface of the substrate.

[0006] In another embodiment, a method for processing a substrate is provided. The method includes positioning the substrate on a substrate support disposed within a processing volume of a processing chamber. The method further includes flowing a process gas into the processing volume, the process gas including a hydrocarbon gas and a diluent gas. The method further includes maintaining the processing volume at a pressure less than about 20 mTorr. The method further includes forming a plasma of the process gas by applying RF AC power to a first electrode of the processing chamber, the RF AC power being between about 500 W and 5 kW and having a frequency between about 350 kHz and about 100 MHz, and applying pulsed DC power to a second electrode of the processing chamber, the pulsed DC power being between about 200 W and about 15 kW pulsed at a frequency of about 1 kHz. The method further includes maintaining the substrate support at a temperature less than about 100° C. The method further includes exposing a surface of the substrate to the plasma. The method further includes depositing an amorphous carbon layer on the surface of the substrate.

[0007] In another embodiment, a carbon hard mask is provided. The carbon hard mask includes an amorphous carbon layer disposed on a surface of a substrate. The amorphous carbon layer has a density of about 1.8 g / cm. 3 , a Young's modulus greater than about 150 GPa, and a membrane stress less than about 500 MPa. [Brief explanation of the drawings]

[0008] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, will be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure, which may also admit of other equally effective embodiments.

[0009] [Figure 1]1 is a schematic cross-sectional view of an exemplary processing chamber used to perform the methods described herein, according to one embodiment. [Figure 2] FIG. 1 is a flow diagram of a method for depositing an amorphous carbon layer, according to one embodiment. [Figure 3] 3 illustrates a carbon hard mask formed from an amorphous carbon layer deposited according to the method illustrated in FIG. 2, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present disclosure relate to methods for depositing amorphous carbon layers on substrates, including over layers previously formed on the substrate, using a plasma-enhanced chemical vapor deposition (PECVD) process. In particular, the methods described herein utilize a combination of RF AC power and pulsed DC power to generate a plasma that deposits amorphous carbon layers with a high ratio of sp3 (diamond-like) carbon to sp2 (graphitic) carbon. These methods also offer lower process pressures, lower process temperatures, and higher throughputs, each of which, alone or in combination, can further increase the relative fraction of sp3 carbon in the deposited amorphous carbon layer. As a result of the higher sp3 carbon fraction, the methods described herein provide amorphous carbon layers with improved density, stiffness, etch selectivity, and film stress compared to amorphous carbon layers deposited by conventional methods.

[0011] 1 is a schematic cross-sectional view of an exemplary process chamber 100 that may be used to perform the methods provided herein, according to one embodiment. Other exemplary process chambers that may be used to perform the methods described herein include the RADION 100, available from the assignee of the present invention, having a location in Santa Clara, California. TM , PRODUCER®, and SYM3 TM Processing equipment, as well as suitable deposition chambers from other manufacturers, are included.

[0012] The processing chamber 100 includes a lid assembly 101, a sidewall 102, and a chamber base 104. The lid assembly 101 includes a chamber lid 106, a showerhead 107 coupled to and in electrical communication with the chamber lid 106, and an electrical insulating ring 108 disposed between the chamber lid 106 and the sidewall 102. The showerhead 107, the sidewall 102, and the chamber base 104 together define a processing volume 105. In one embodiment, the chamber lid 106 and the showerhead 107 are formed from an electrically conductive material, such as aluminum. A gas inlet 109 is disposed through the chamber lid 106 and is fluidly coupled to a gas source 110. The showerhead 107 has a plurality of openings 111 disposed therethrough and is used to uniformly distribute processing gases from the gas source 110 into the processing volume 105. In other embodiments, the processing chamber 100 does not include a showerhead 107, and processing gases are delivered to the processing volume 105 through one or more gas inlets disposed through the chamber lid 106 or sidewall 102.

[0013] The process volume 105 is fluidly coupled to a vacuum source 112, which may be one or more dedicated vacuum pumps, through a vacuum outlet 114 that maintains the process volume 105 at sub-atmospheric pressure and evacuates process and other gases therefrom during processing. A substrate support 115 disposed within the process volume 105 is disposed on a movable support shaft 116 that extends through the chamber base 104. Here, the process chamber 100 is configured to facilitate transfer of a substrate 117 to and from the substrate support 115 through an opening 118 in one of the sidewalls 102 that is sealed with a door or valve (not shown) during substrate processing.

[0014] The substrate 117 is maintained at a desired processing temperature using one or both of a heater 119 and one or more cooling channels 120. The heater 119 may be a resistive heater, and the one or more cooling channels 120 are disposed within the substrate support 115. The one or more cooling channels 120 are fluidly coupled to a coolant source (not shown), such as a refrigerant source or modified water source having a relatively high electrical resistance. The heater 119 is in electrical communication with a power supply (not shown) configured to provide power to the heater 119 and elevate the temperature of the substrate support 115.

[0015] In some embodiments, one or more electrodes 124 are embedded in the dielectric material of the substrate support 115. The one or more electrodes are electrically coupled to a power source 121. The power source 122 is electrically coupled to the showerhead 107. In embodiments that do not include a showerhead, the power source 122 is electrically coupled to the lid assembly 106. Each of the power sources 121 and 122 can be a continuous wave (CW) RF power source, a pulsed RF power source, a DC power source, and / or a pulsed DC power source. In one embodiment, the power source 121 is a CW RF power source and the power source 122 is a pulsed DC power source. In another embodiment, the power source 121 is a pulsed DC power source and the power source 122 is a pulsed RF power source. Although only two power sources 121 and 122 are shown, it is contemplated that more power sources may be coupled to electrodes of the substrate support 115 or the lid assembly 101, as needed. For example, a pulsed DC power source may be coupled to electrodes of both the substrate support 115 and the lid assembly 101, along with an RF power source coupled to an electrode in the lid assembly 101.

[0016] In one embodiment, plasma 123 is formed and maintained in process volume 105 by supplying RF power from power source 122 to one or more electrodes in lid assembly 101, thereby generating a capacitively coupled plasma 123. Plasma 123 is then modified by supplying DC power from power source 121 to one or more electrodes disposed in substrate support 115. In another embodiment, plasma 123 is formed and maintained by RF power from power source 121 and modified by DC power from power source 122.

[0017] 2 is a flow diagram of a method 200 for depositing an amorphous carbon layer on a surface of a substrate, according to one embodiment. In step 201, the method 200 includes positioning a substrate on a substrate support. The substrate support is disposed in a processing volume of a processing chamber, such as processing chamber 100 depicted in FIG. 1. In step 202, the method 200 includes flowing a processing gas into the processing volume. The processing gas may be a carbon source gas, such as a hydrocarbon gas, e.g., CH, C, H, C, H, or C. 10 , C2H4, C3H6, C4H8, C5H 10 , or a combination thereof, and the process gas also includes a diluent gas, e.g., an inert gas such as Ar, He, Ne, Kr, Xe, or a combination thereof. In some embodiments, the diluent gas includes an inert gas such as a noble gas, N2, H2, or a combination thereof.

[0018] In some embodiments, the ratio of the flow rate of the hydrocarbon gas to the flow rate of the diluent gas is between about 1:10 and about 10:1, e.g., between about 1:5 and about 5:1. For example, in one embodiment, the ratio of the flow rate of C2H2 to the flow rate of He is between about 1:3 and about 3:1. In some embodiments, the diluent gas includes H2, and the ratio of the flow rate of H2 to the hydrocarbon gas is between about 0.5:1 and about 1:10, e.g., between about 1:1 and about 1:5.

[0019] In step 203, the method 200 includes maintaining the process volume at a process pressure between about 0.1 mTorr and about 100 mTorr, e.g., between about 0.1 mTorr and about 50 mTorr, or between about 0.1 mTorr and about 30 mTorr, or between about 0.1 mTorr and about 20 mTorr, or between about 0.1 mTorr and about 15 mTorr, or between about 0.1 mTorr and about 10 mTorr, or less than about 100 mTorr, or less than about 50 mTorr, or less than about 20 mTorr, or less than about 15 mTorr, or less than about 10 mTorr.

[0020] In step 204, the method 200 includes forming and maintaining a plasma of the process gas by applying a first power to a first electrode of the processing chamber and a second power, the second power being pulsed DC power, to a second electrode of the processing chamber. In one embodiment, the first electrode is disposed within the substrate support. In another embodiment, the first electrode is disposed opposite the substrate support, such as within the showerhead or chamber lid of the processing chamber. In one embodiment, the first power is RF AC power between about 500 W and about 5 kW, e.g., about 2500 W. The first power has a frequency between about 350 kHz and about 100 MHz, e.g., 2 MHz or 13.56 MHz.

[0021] In one embodiment, the second electrode is disposed within the substrate support. In another embodiment, the second electrode is disposed on the opposite side of the substrate support. In one embodiment, the second electrode is a showerhead. In one embodiment, the second power is between about 200 W and about 15 kW. In another embodiment, the second power is pulsed at a frequency of about 1 kHz. In another embodiment, the second power has a duty cycle of about 50%.

[0022] As discussed above, providing pulsed DC power from the substrate support is believed to increase the uniformity of ion energy in the plasma and subsequently increase the concentration of sp3 carbon in the deposited amorphous carbon layer. As described below with reference to FIG. 3, amorphous carbon layers with higher sp3 concentrations exhibit desirable properties, such as higher density, higher Young's modulus, and lower film stress, compared to conventionally deposited amorphous carbon layers. Furthermore, as discussed above, providing pulsed DC power to a second electrode on the opposite side of the substrate support, such as a showerhead, is believed to increase secondary electron emission from the second electrode, further reducing film stress in the deposited amorphous carbon layer.

[0023] In step 205, the method 200 includes maintaining the substrate support, and thus the substrate disposed thereon, at a temperature between about -50°C and about 350°C, e.g., between about -50°C and about 150°C, between about -50°C and about 100°C, between about -50°C and about 50°C, between about -25°C and about 25°C, or less than about 350°C, e.g., less than about 200°C, less than about 150°C, less than 100°C, or less than about 50°C.

[0024] In step 206, the method 200 includes exposing the surface of the substrate to a plasma. In step 207, the method 200 includes depositing an amorphous carbon layer on the surface of the substrate.

[0025] 2 shows an example flow diagram, it should be noted that variations of method 200 are contemplated. For example, step 205 may occur before step 202, 203, or 204. Furthermore, one or more of steps 202-207 may occur simultaneously.

[0026] Figure 3 illustrates a carbon hard mask 303 deposited according to the method illustrated in Figure 2, according to one embodiment. The carbon hard mask 303, illustrated as a patterned carbon hard mask, includes an amorphous carbon layer 302 having a plurality of openings 304 formed therein disposed on a surface to be patterned of a substrate 301. The substrate 301 or one or more material layers thereof may be formed from one or a combination of crystalline silicon, silicon oxide, silicon oxynitride, silicon nitride, strained silicon, silicon germanium, tungsten, titanium nitride, doped or undoped polysilicon, carbon-doped silicon oxide, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and low-k dielectric materials.

[0027] The amorphous carbon layer 302 has a thickness of between about 1 kA and about 40 kA, e.g., between about 10 kA and about 40 kA, or between about 10 kA and about 30 kA, and a current of about 1.8 g / cm 3 and a Young's modulus greater than about 150 GPa. In one embodiment, amorphous carbon layer 302 has a tensile or compressive film stress less than about 500 MPa. In some implementations, each of openings 304 has an aspect ratio (i.e., the ratio of height 306 to width 305) greater than about 2:1, e.g., greater than about 3:1, greater than about 4:1, greater than about 5:1, greater than about 6:1, greater than about 7:1, greater than about 8:1, greater than about 9:1, or greater than about 10:1.

[0028] The methods described herein and amorphous carbon layers deposited according to such methods exhibit desirable properties for carbon hard mask applications. The deposited amorphous carbon layers exhibit a high ratio of sp3 (diamond-like) carbon to sp2 (graphitic) carbon. These methods also offer lower processing pressures, lower processing temperatures, and higher throughputs, each of which, alone or in combination, can further increase the relative fraction of sp3 carbon in the deposited amorphous carbon layer. As a result of the higher sp3 carbon fraction, the methods described herein provide amorphous carbon layers with improved density, stiffness, etch selectivity, and film stress compared to amorphous carbon layers deposited by conventional methods.

[0029] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. 1. A method for processing a substrate, comprising: Positioning a substrate on a substrate support disposed within a processing volume of a processing chamber; flowing a process gas including a hydrocarbon gas and a diluent gas into a processing volume; maintaining the process volume at a pressure less than 100 mTorr; forming a plasma of the process gas by applying a first power to a first electrode of the processing chamber and applying a second power to a second electrode of the processing chamber, the second power being a pulsed DC power, the second electrode being disposed opposite the substrate support; maintaining the substrate support at a temperature less than 350° C.; exposing a surface of the substrate to a plasma; and Depositing an amorphous carbon layer on a surface of a substrate. A method comprising:

2. The amorphous carbon layer is 1.8 g / cm ３ 13. The method of claim 1, wherein the sintered body has a density greater than 1.0 and a Young's modulus greater than 150 GPa.

3. The method of claim 1 , wherein the amorphous carbon layer has a film stress of less than 500 MPa.

4. The hydrocarbon gas is CH ４ , C ２ H ２ , C ３ H ８ , C ４ H １０ , C ２ H ４ , C ３ H ６ , C ４ H ８ , C ５ H １０ 10. The method of claim 1, wherein the flow ratio of the hydrocarbon gas to the diluent gas is between 1:10 and 10:

1.

5. 10. The method of claim 1, wherein the temperature is less than 100° C. and the pressure is less than 20 mTorr.

6. Dilution gas is H ２ Including H ２ 2. The method of claim 1, wherein the flow ratio of the gas to the hydrocarbon gas is between 0.5:1 and 1:

10.

7. 2. The method of claim 1, wherein the first power is an RF AC power between 500 W and 5 kW and has a frequency between 350 kHz and 100 MHz, and the second power is between 200 W and 15 kW and pulsed at a frequency of 1 kHz.

8. The method of claim 1 , wherein the first electrode is disposed within a substrate support.

9. The method of claim 1 , wherein the second electrode is a showerhead.

10. 1. A method for processing a substrate, comprising: Positioning a substrate on a substrate support disposed within a processing volume of a processing chamber; flowing a process gas including a hydrocarbon gas and a diluent gas into a processing volume; maintaining the process volume at a pressure less than 20 mTorr; forming a plasma of the process gas by applying RF AC power to a first electrode of the processing chamber, the RF AC power being between 500 W and 5 kW and having a frequency between 350 kHz and 100 MHz, and applying pulsed DC power to a second electrode of the processing chamber, the second electrode being disposed opposite the substrate support, the pulsed DC power being between 200 W and 15 kW; maintaining the substrate support at a temperature less than 350° C.; exposing a surface of the substrate to a plasma; and Depositing an amorphous carbon layer on a surface of a substrate. A method comprising:

11. The hydrocarbon gas is CH ４ , C ２ H ２ , C ３ H ８ , C ４ H １０ , C ２ H ４ , C ３ H ６ , C ４ H ８ , C ５ H １０ or a combination thereof.

12. Dilution gas is H ２ Including H ２ 12. The method of claim 11, wherein the flow ratio of the gas to the hydrocarbon gas is between 0.5:1 and 1:

10.

13. The method of claim 10 , wherein the first electrode is disposed within a substrate support.

14. 1. A method for producing a carbon hard mask comprising an amorphous carbon layer on a surface of a substrate, the method comprising: Positioning a substrate on a substrate support disposed within a processing volume of a processing chamber; flowing a process gas including a hydrocarbon gas and a diluent gas into a processing volume; maintaining the process volume at a pressure less than 100 mTorr; forming a plasma of the process gas by applying a first power to a first electrode of the processing chamber and applying a second power to a second electrode of the processing chamber, the second power being a pulsed DC power, the second electrode being disposed opposite the substrate support; maintaining the substrate support at a temperature less than 350° C.; exposing a surface of the substrate to a plasma; and Depositing an amorphous carbon layer on a surface of a substrate. Including, An amorphous carbon layer having a density exceeding 1.8 g / cm ３ a method having a Young's modulus exceeding 150 GPa and a film stress of less than 500 MPa.

15. 15. The method of claim 14, wherein the amorphous carbon layer has a plurality of openings formed therethrough, each of the plurality of openings having a height to width ratio of greater than 2:

1.

16. 1. A method for forming an amorphous carbon layer on a surface of a substrate, comprising the steps of: Positioning a substrate on a substrate support disposed within a processing volume of a processing chamber; flowing a process gas comprising a hydrocarbon gas and a diluent gas into a processing volume; maintaining the process volume at a pressure less than 100 mTorr; forming a plasma of the process gas by applying a first power to a first electrode of the processing chamber and applying a second power to a second electrode of the processing chamber, the second power being a pulsed DC power, the second electrode being disposed opposite the substrate support; maintaining the substrate support at a temperature less than 200° C.; exposing a surface of the substrate to a plasma; and Depositing an amorphous carbon layer on a surface of a substrate. A method comprising:

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