KR100989107B1 - Method and apparatus for multilayer photoresist dry development - Google Patents

Abstract

The present invention includes the steps of introducing a process gas comprising ammonia (NH ₃ ) and the passivation gas; Forming a plasma from the processing gas; And a method of etching an organic antireflective coating (ARC) layer on a substrate in a plasma processing system comprising exposing the substrate to a plasma. Process gases are, for example, NH ₃ and C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ Hydrocarbon gas, such as one or more of H ₈ , C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . In addition, the treatment chemical may further comprise a helium additive. The invention also includes: forming a thin film on a substrate; Forming an ARC layer on the thin film; Forming a photoresist pattern on the ARC layer; And transferring the photoresist pattern to the ARC layer by an etching process using a processing gas comprising ammonia (NH ₃ ) and a passivation gas. It's about how.

Description

METHOD AND APPARATUS FOR MULTILAYER PHOTORESIST DRY DEVELOPMENT}

This application is directed to US Provisional Patent Application No. 60 / 458,430, filed March 31, 2003, US Provisional Application No. 60 / 484,225, filed May 5, 2003, and August 14, 2003. And non-provisional patent application No. 10 / 640,577, the entire contents of which are hereby incorporated by reference. This application is filed on December 23, 2002, co-pending, entitled "Methods and Apparatus for Double Layer Photoresist Dry Development," Application No. 60 / 435,286, the entire contents of which are incorporated herein by reference. Related to).

The present invention relates to a method and apparatus for plasma treating a substrate, and more particularly to a method for dry development of multilayer photoresists.

During semiconductor processing, a (dry) plasma etch process is used to remove or etch material within vias or contacts, which are either fine lines or patterned on a silicon substrate. Can be. Plasma etching processing generally involves positioning an overly patterned protective layer (eg, a photoresist layer) on a semiconductor substrate in a processing chamber. Once the substrate is located in the chamber, an ionizable decomposable gas mixture is introduced into the chamber at a pre-specified flow rate and throttles the vacuum pump to obtain ambient processing pressure. Subsequently, a fraction of the gas species present is heated through the transmission of inductively or capacitively radio frequency (RF) power, or microwave power using, for example, electron cyclotron resonance (ECR). When ionized by the electrons, the plasma is formed. In addition, the heated electrons decompose some species of ambient gas species and produce reactive species (s) suitable for exposed surface etching chemistry. Once the plasma is formed, the selected surface of the substrate is etched by the plasma. This treatment is adjusted to achieve the appropriate conditions, including the desired concentration of reactants and ion populations, to etch various features (e.g., trenches, vias, contacts, etc.) within selected regions of the substrate. . Such substrate materials which require etching include silicon dioxide (SiO ₂ ), low-k dielectric materials, poly-silicon and silicon nitride.

The present invention relates to a method and apparatus for plasma treating a substrate, and to a method and apparatus for multilayer photoresist dry development. The invention also relates to the multilayer mask itself.

In one aspect of the invention, a method and apparatus for etching an anti-reflective coating (ARC) layer on a substrate in a plasma processing system is described. A process gas is introduced which comprises one or more gases which collectively comprise ammonia (NH ₃ ) and a passivation gas. Plasma is formed from the processing gas in the plasma processing system. The substrate is exposed to the plasma.

In another aspect of the present invention, a method and apparatus for forming a bilayer mask for etching a thin film on a substrate are described. The thin film is formed on the substrate. An antireflective coating (ARC) layer is formed on the thin film. A photoresist pattern is formed on the ARC layer. By etching the ARC layer using a process gas comprising one or more gases collectively comprising ammonia (NH ₃ ) and a passivation gas, the photoresist pattern is transferred to the ARC layer.

In addition, a method of smoothing sidewalls in a multilayer mask on a substrate in a plasma processing system includes: introducing a processing gas comprising one or more gases collectively comprising ammonia (NH ₃ ) and a passivation gas; Forming a plasma from the processing gas in the plasma processing system; And exposing the substrate to the plasma, wherein the passivation gas facilitates the formation of a passivation film on the sidewalls of the multilayer mask, thereby smoothing the roughness surface of the sidewalls.

1A, 1B and 1C show schematic diagrams of a general procedure for pattern etching a thin film;

2 shows a simple schematic diagram of a plasma processing system according to an embodiment of the present invention;

3 shows a schematic diagram of a plasma processing system according to another embodiment of the present invention;

4 shows a schematic diagram of a plasma processing system according to another embodiment of the present invention;

5 shows a schematic diagram of a plasma processing system according to another embodiment of the present invention;

6 shows a schematic diagram of a plasma processing system according to another embodiment of the present invention;

7 illustrates a method of etching an antireflective coating (ARC) layer on a substrate in a plasma processing system in accordance with an embodiment of the present invention;

8 illustrates a method of forming a bilayer mask for etching a thin film on a substrate in accordance with another embodiment of the present invention;

9A and 9B show schematic diagrams of multilayer masks.

Detailed Description of Some Embodiments

In the material processing method, the pattern etching is subsequently applied to apply a thin layer of photosensitive material such as photoresist to the upper surface of the substrate and to provide a mask for transferring the pattern to the underlying thin film on the substrate during etching. Patterning is done. Patterning of the photosensitive material generally involves exposing the photosensitive material by means of a radiation source through a reticle (and associated optics), for example using a microlithography system, and then using a developing solvent to irradiate the photosensitive material (positive photoresist). As in the case of) or non-irradiation regions (as in the case of negative resist). With a multilayer mask, the shape can be etched in the thin film. For example, as shown in FIGS. 1A-C, a bilayer mask 6 comprising a photosensitive layer 3 with a pattern 2 formed using conventional lithography techniques and an organic antireflective coating (ARC) layer 7. ) May be used as a mask for etching the thin film 4 on the substrate 5, and the mask pattern 2 of the photosensitive layer 3 may be subjected to an individual etching step prior to the main etching step of the thin film 4. Is transferred to the ARC layer 7.

In one embodiment, a processing gas comprising ammonia (NH ₃ ) and a passivation gas is used in a double layer photoresist dry development method. For example, the passivation gas may be C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , Hydrocarbon gas, such as one or more of C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ , C ₆ H ₁₂ , and the like.

Although the above embodiment describes the etching of the thin film 4 on the substrate 5, it can be etched into the substrate 5 itself, with or without the thin film 4.

According to one embodiment, a plasma processing chamber 10, a diagnostic system 12 coupled to the plasma processing chamber 10, and a controller 14 coupled to the diagnostic system 12 and the plasma processing chamber 10. A plasma processing system 1 comprising a is shown in FIG. 2. The controller 14 is arranged to perform a processing method comprising one or more of the above-identified chemistries to etch the organic ARC layer.

In addition, the controller 14 is arranged to receive one or more endpoint signals from the diagnostic system 12 and post-process one or more endpoint signals to accurately determine the endpoint of the process. In the embodiment being described, the plasma processing system 1 shown in FIG. 2 uses plasma for material processing. The plasma processing system 1 may comprise an etching chamber.

According to the embodiment of FIG. 3, the plasma processing system 1a comprises a plasma processing chamber 10, a substrate holder 20 to which the substrate 25 to be processed is attached, and a vacuum pumping system 30. Can be. Substrate 25 may be, for example, a semiconductor substrate, a wafer or a liquid crystal display. The plasma processing chamber 10 may be arranged, for example, to easily generate a plasma in the processing region 15 adjacent to the substrate 25 surface. An ionizable gas or gas mixture is introduced through a gas injection system (not shown) and the processing pressure is adjusted. For example, an adjustment mechanism (not shown) can be used to adjust the vacuum pumping system 30. Plasma may be used to make a material specific to a given material treatment and / or to assist in the removal of material from the exposed surface of the substrate 25. The plasma processing system 1a may be arranged to process a 200 mm substrate, a 300 mm substrate, or more substrates.

Substrate 25 may be attached to substrate holder 20 via, for example, an electrostatic clamping system. The substrate holder 20 also receives, for example, heat from the substrate holder 20, transfers heat to a heat exchanger system (not shown), or transfers heat from the heat exchanger system upon heating. It may further comprise a cooling system comprising a recirculating coolant stream. In addition, gas may be delivered to the backside of the substrate 25 via a backside gas system, for example, to improve the gap-gap thermal conductance between the substrate 25 and the substrate holder 20. Can be. Such a system can be used when temperature control of the substrate is required at elevated or reduced temperatures. For example, the backside gas system can comprise a two-zone gas distribution system, which can independently change the helium gas gap pressure between the center and the edge of the substrate 25. Can be. In another embodiment, a heating / cooling element, such as a resistive heating element, or a thermo-electric heater / cooler, the substrate holder 20, the chamber wall of the plasma processing chamber 10, and any in the plasma processing system 1a. Can be included in other components

In the embodiment shown in FIG. 3, the substrate holder 20 may comprise an electrode whose RF power is coupled to the processing plasma in the processing space 15. For example, substrate holder 20 may be electrically biased at RF voltage by transferring RF power from RF generator 40 through impedance match network 50 to substrate holder 20. The RF bias can heat the electrons to form and maintain the plasma. In this arrangement, the system can operate as a reactive ion etching (RIE) reactor, with the chamber and the top gas injection electrode serving as a ground plane. Typical frequencies of RF bias can range from 0.1 MHz to 100 MHz. RF systems for plasma processing are well known to those skilled in the art.

Optionally, RF power is applied to the substrate holder electrode at multiple frequencies. The impedance match network 50 also serves to enhance the transfer of RF power to the plasma in the plasma processing chamber 10 by reducing the reflected power. Match network topologies (e.g., L-type, [pi] -type, T-type, etc.) and automatic adjustment methods are well known to those skilled in the art.

The vacuum pump system 30 may include, for example, a turbo-molecular vacuum pump (TMP) capable of pumping speeds of up to 5000 liters per second (and more), and a gate valve for regulating chamber pressure. In a conventional plasma processing apparatus used for dry plasma etching, 1000 to 3000 liters TMP per second are generally used. TMPs are useful for low pressure treatments, generally less than 50 mTorr. For high pressure treatment (ie, 100 mTorr or more), mechanical booster pumps and dry roughing pumps can be used. In addition, an apparatus (not shown) for monitoring chamber pressure may be coupled to the plasma processing chamber 10. As the pressure measuring device, for example, a Type 628B Baratron absolute capacitance manometer available from MKS Instruments, Inc. (Andover, MA) may be used.

The controller 14 is provided with a regulated voltage sufficient to deliver and activate inputs to the microprocessor, memory, and plasma processing system 1a and to monitor the outputs from the plasma processing system 1a. It consists of a digital I / O port that can generate a. The controller 14 also includes an RF generator 40, an impedance match network 50, a gas injection system (not shown), a vacuum pump system 30 and a backside gas delivery system (not shown), a substrate / substrate holder. It may be coupled to and exchange information with a temperature measurement system (not shown), and / or an electrostatic flapping system (not shown). For example, by using a program stored in a memory, the method of etching an organic ARC layer can be performed by activating an input signal to the above-described component of the plasma processing system 1a. One example of the controller 14 is DELL PRECISION WORKSTATION 610 ^™ , available from Dell Corporation, Austin, Texas.

Diagnostic system 12 may include an optical diagnostic system (not shown). The optical diagnostic subsystem may comprise a detector such as a (silicon) photodiode or photo mulitiplier tube (PMT) for measuring the intensity of light emitted from the plasma. Diagnostic system 12 may further include an optical filter, such as a narrow-band interference filter. In an alternate embodiment, the diagnostic system 12 includes a line CCD (charge coupled device), a CID (charge injection device) array, and light dispersion such as a grating or prism. It may include one or more of the devices. In addition, the diagnostic system 12 may include a light spectrum such as a monochromator (eg, a grating / detector system) for measuring light at a given wavelength, or a device as described, for example, in US Pat. No. 5,888,337. And spectrometers (including, for example, rotational gratings) to measure.

The diagnostic system 12 may include a high resolution optical emission spectroscopy (OES) sensor, such as a peak sensor system or manufactured by Bery Instruments. Such OES sensors have a broad spectrum ranging from ultraviolet (UV), visible (VIS), and near infrared (NIR) light spectra. The resolution is about 1.4 Angstroms, meaning the sensor can collect 5550 wavelengths from 240nm to 1000nm. For example, the OES sensor may comprise a high sensitivity miniature fiber optic UV-VIS-NIR spectrometer in which 2048 pixel linear CCD arrays are integrated one after the other.

The spectrometer receives the light transmitted through the single and bundle optical fibers, and the optical output signal from the optical fiber is dispersed in the line CCD array using fixed gratings. Similar to the arrangement described above, light passing through the optical vacuum window is focused through the convex spherical lens at the input end of the optical fiber. Three spectrometers, each specifically tuned for a given spectral range (UV, VIS and NIR), form a sensor for the processing chamber. Each spectrometer includes an independent A / D converter. Finally, depending on the sensor utilization, the full emission spectrum can be recorded every 0.1 to 1.0 seconds.

In the embodiment shown in FIG. 4, the plasma processing system 1b may be similar to the embodiment of FIG. 2 or 3, for example, and in addition to the components described with reference to FIGS. It may further comprise a stationary or mechanical or electrical rotating magnetic field system 60 to potentially increase and / or improve plasma treatment uniformity. In addition, the controller 14 may be coupled to the magnetic field system 60 to adjust the rotational speed and the magnetic field strength. Design and performance of rotating magnetic fields are well known to those skilled in the art.

In the embodiment shown in FIG. 5, the plasma processing system 1c may be similar to, for example, the embodiment of FIG. 2 or FIG. 3, wherein RF power is coupled to the impedance match network 74 from the RF generator 72. It can be made by further comprising an upper electrode 70 that can be coupled through. Typical frequencies for applying RF power to the upper electrode may range from 0.1 MHz to 200 MHz. Also, a typical frequency for applying power to the lower electrode can range from 0.1 MHz to 100 MHz. The controller 14 is also coupled to the RF generator 72 and the impedance match network 74 to control the application of RF power to the upper electrode 70. The design and performance of the top electrode is well known to those skilled in the art.

In the embodiment shown in FIG. 6, the plasma processing system 1d may be similar to the embodiment of FIG. 2 or 3, for example, in which RF power is applied to the impedance match network 84 via the RF generator 82. It may further comprise an induction coil 80 coupled through. RF power is inductively coupled from the induction coil 80 through the dielectric window (not shown) to the plasma processing region 15. Typical frequencies for applying RF power to the induction coil 80 may range from 10 MHz to 100 MHz. Similarly, a typical frequency for applying power to chuck electrodes may range from 0.1 MHz to 100 MHz. In addition, a slotted Faraday shield (not shown) may be used to reduce capacitive coupling between the induction coil 80 and the plasma. The controller 14 is also coupled to the RF generator 82 and the impedance match network 84 to control the application of power to the induction coil 80. In an alternate embodiment, the induction coil 80 is a "spiral" coil or "pancake" that communicates with the plasma processing region 15, such as in a transformer coupled plasma (TCP) reactor. Mold "coil. Design and implementation of inductively coupled plasma (ICP) sources, or transformer coupled plasma (TCP) sources, are well known to those skilled in the art.

Optionally, the plasma can be formed using electron cyclotron resonance (ECR). In another embodiment, the plasma is formed due to launching helicon waves. In another embodiment, the plasma is formed due to propagating surface waves. Each plasma source described above is well known to those skilled in the art.

In the following, a method of etching an organic ARC layer using a plasma processing apparatus is discussed. For example, the plasma processing apparatus may comprise various elements as described in FIGS. 2-6, and combinations thereof.

In one embodiment, the method of etching the organic ARC layer is NH ₃ and C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C Hydrocarbon gas, such as one or more of ₄ H ₆ , C ₄ H ₈ , C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . . For example, the process parameter space may include a chamber pressure of 20 mTorr to 1000 mTorr, NH ₃ process gas flow rate of 50 sccm to 1000 sccm, hydrocarbon process gas flow rate of 5 to 100 sccm, and an upper electrode of 500 W to 2000 W (e.g. 70) RF bias, and the lower electrode (eg, device 20 of FIG. 5) RF bias of 10W to 500W. In addition, the upper electrode bias frequency may be 0.1MHz to 200MHz, for example 60MHz. In addition, the lower electrode bias frequency may be 0.1MHz to 100MHz, for example 2MHz.

For example, there is a method of etching the organic ARC layer using a plasma processing apparatus as shown in FIG. However, the scope of the method discussed by this example should not be limited. Table 1 shows that chamber pressure = 100 mTorr; Upper electrode RF power = 1200 W; Bottom electrode RF power = 100 W; Process gas flow rate NH ₃ / C ₂ H ₄ = 450/50 sccm; An electrode gap of 55 mm between the bottom surface of the electrode 70 (see FIG. 5) and the top surface of the substrate 25 on the substrate holder 20; Bottom electrode temperature (eg, substrate holder 20 of FIG. 5) = 20C; Upper electrode temperature (eg, electrode 70 of FIG. 5) = 60C; Chamber wall temperature = 50C; Rear helium pressure center / edge = 10/35 Torr; And the critical dimensions of the appearance etched into the organic ARC layer using an exemplary processing method with an etching time of 180 seconds.

(Photoresist-PR; Critical Dimension-CD) NH ₃ / C ₂ H ₄ center edge Residual Top PR 478 nm 493 nm Bottom CD / Bias-MC 154/6 nm 147 / -3 nm Floor CD / Bias-CA 138 / -5 nm 134 / -9 nm

 Table 1 shows the thickness of the photoresist remaining after the ARC layer etch, the top and bottom critical dimensions of the ARC shape, and the critical dimension bias (bias, CD change from top to bottom (ie negative bias reduces CD). Positive bias indicates CD increase), and the like (for both metal contact (MC) and contact (CA)). It also reports data at the center and edge. The data demonstrates that the CD and the maintenance of the potential for reducing the CD are successful.

In alternative embodiments, the treatment chemical may further comprise helium (He). The introduction of helium in the treatment can reduce the outer sidewall roughness.

In general, the design of an experiment (DOE) technique can be used to determine the etch time; However, endpoint detection may be used to determine the etching time. One possible method of endpoint detection is to monitor the portion of the emitted light spectrum from the plasma region that indicates when the plasma chemistry changes because the ARC layer etch is substantially nearly complete and in contact with the underlying material film. For example, the spectral portion indicative of such a change consists of a wavelength of 387.2 nm (carbon-nitrogen (CN)) and can be measured using optical emission spectroscopy (OES). After the emission level corresponding to this frequency exceeds the specified threshold (eg, substantially falls to zero or increases above a certain level), the endpoint can be considered complete. Other wavelengths that provide endpoint information are also available. In addition, the etching time may be extended to include an over-etching period, wherein the over-etching period is composed of a portion (ie, 1 to 100%) between the time associated with the start of the etching process and the end point detection. .

7 shows a flowchart of a method of etching an antireflective coating (ARC) layer on a substrate in a plasma processing system according to an embodiment of the present invention. The procedure 400 begins at 410 introducing a process gas into a plasma processing system, which process gas comprises an ammonia (NH ₃ ) containing gas and a passivation gas. For example, the passivation gas may be C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , Hydrocarbon gas, such as one or more of C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . Optionally, the processing gas may further comprise helium (He).

At 420, the plasma is formed from the processing gas in the plasma processing system using, for example, any of the systems shown in FIGS. 2-6, or a combination thereof.

At 430, the substrate comprising the ARC layer is exposed to a plasma formed within 420. After the first period, procedure 400 ends. For example, the primary period during which a substrate comprising an ARC layer is exposed to plasma is generally indicated by the time required to etch the ARC layer, or the time required to transfer the photoresist pattern to the ARC layer. In general, the first period required to transfer the photoresist pattern through the thickness of the ARC layer is predetermined. Optionally, the primary period may be further increased by the secondary period or the over-etching period. As noted above, the over-etching time may comprise a portion of the time, such as 1 to 100% of the primary period, the over-etching period comprising an extension of the etch beyond the detection of the end point. Can be.

8 illustrates a method of forming a bilayer mask for etching a thin film on a substrate in a plasma processing system in accordance with another embodiment of the present invention. This method is shown in flow diagram 500, beginning at 510, forming a thin film on a substrate. The thin film may comprise an oxide layer, such as silicon dioxide (SiO ₂ ), and may be formed by various processes including chemical vapor deposition (CVD).

At 520, an antireflective coating (ARC) layer is formed on the substrate upper thin film. The ARC layer is an organic ARC layer that is formed using conventional techniques such as, for example, spin coating systems.

At 530, a photoresist pattern is formed on the substrate top ARC layer. The photoresist film can be formed using conventional techniques such as a photoresist spin coating system. The pattern can be formed in the photoresist film by using conventional techniques such as stepping micro-lithography systems, and developing solvents.

At 540, the photoresist pattern is transferred to the ARC layer to form a bilayer mask. Pattern transfer is completed using a dry etching technique, and the etching process is performed in a plasma processing system using a processing gas containing ammonia (NH ₃ ) containing gas and a passivation gas. For example, the passivation gas may be C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ It may comprise a hydrocarbon gas, such as one or more of C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . Optionally, the processing gas as described above may further comprise helium (He). The plasma is formed from the processing gas in the plasma processing system using, for example, any of the systems shown in FIGS. 2-6, and the substrate comprising the ARC layer is exposed to the formed plasma. The primary period during which the substrate comprising the ARC layer is exposed to the plasma is generally indicated by the time required to etch the ARC layer, or the time required to transfer the photoresist pattern to the ARC layer. In general, the first period required to transfer the photoresist pattern through the thickness of the ARC layer is predetermined. In general, however, the primary period may be further increased by the secondary period or the over-etching period. As noted above, the over-etching time may comprise a portion of the time, such as 1 to 100% of the primary period, the over-etching period comprising an extension of the etch beyond the detection of the end point. Can be.

9A and 9B show side and top views, respectively, of an etched multilayer mask. The shape 600 comprises a sidewall 610 through the photosensitive layer 640 and the ARC layer 650, where a surface roughness 620 is formed during etching. The passivation gas facilitates the formation of the passivation film 630 to smooth the surface roughness 620 of the etched multilayer mask; See FIG. 9B.

Although only certain embodiments of the invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible within these embodiments without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are included within the scope of the present invention.

Claims (35)

Introducing a process gas comprising a passivation gas comprising a hydrocarbon gas and one or more gases collectively comprising ammonia (NH ₃ ); Forming a plasma from the processing gas in a plasma processing system; And Exposing a substrate to the plasma Including, The passivation gas is C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , C ₄ H An anti-reflective coating (ARC) layer on the substrate in a plasma processing system, comprising one or more of ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H _10, and C ₆ H ₁₂ . How to etch. delete delete The method of claim 1, Wherein said processing gas further comprises helium. The method of claim 1, The exposure of the substrate to the plasma is performed during a first period of time. The method of claim 5, Wherein said first period of time is determined by endpoint detection. The method of claim 6, Wherein said endpoint detection comprises optical emission spectroscopy. The method of claim 5, The first period of time corresponds to a time for etching the ARC layer and is extended by a second period of time. The method of claim 8, The second period is a fraction of the first period. Forming a thin film on the substrate; Forming an anti-reflective coating (ARC) layer on the thin film; Forming a photoresist pattern on the ARC layer; And Transferring the photoresist pattern to the ARC layer by etching the ARC layer using a passivation gas comprising a hydrocarbon gas and a processing gas comprising one or more gases collectively comprising ammonia (NH ₃ ). A method of forming a bilayer mask for etching a thin film on a substrate, comprising. delete The method of claim 10, The passivation gas is C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . The method of claim 10 or 12, Wherein said processing gas further comprises helium. The method of claim 10, Wherein said etching of said substrate is performed during a first period of time. 15. The method of claim 14, Wherein said first period of time is determined by endpoint detection. The method of claim 15, Wherein said endpoint detection comprises optical emission spectroscopy. 15. The method of claim 14, The first period of time corresponds to a time for etching the ARC layer and is extended by a second period of time. The method of claim 17, The second period is a fraction of the first period. A plasma processing chamber for facilitating the formation of a plasma from the processing gas; A regulator coupled to the plasma processing chamber and configured to perform a treatment with the processing gas Including, The process gas comprises a passivation gas comprising a hydrocarbon gas and one or more gases collectively comprising ammonia (NH ₃ ), The passivation gas is C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , C ₄ H A plasma for etching an anti-reflective coating (ARC) layer on a substrate, comprising one or more of ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H _10, and C ₆ H ₁₂ . Processing system. The method of claim 19, The system further comprises a diagnostic system coupled to the plasma processing chamber and coupled to the regulator. The method of claim 20, The diagnostic system is to receive a signal related to light emitted from the plasma. delete delete The method of claim 19, Wherein said processing gas further comprises helium. The method of claim 20, Wherein the regulator causes the substrate to be exposed to the plasma for a first period of time. 26. The method of claim 25, The first period of time is determined by endpoint detection determined by the diagnostic system. The method of claim 26, Wherein said diagnostic system comprises an optical emission spectroscopy device. 26. The method of claim 25, The first period of time corresponds to a time for etching the ARC layer and is extended by a second period of time. The method of claim 28, The second period of time is a fraction of the first period of time. Introducing a process gas comprising a passivation gas comprising a hydrocarbon gas and one or more gases collectively comprising ammonia (NH ₃ ); Forming a plasma from the processing gas in a plasma processing system; And Exposing a substrate to the plasma Including, Wherein the passivation gas facilitates formation of a passivation film on the sidewalls of the multilayer mask to smooth the surface roughness of the sidewalls. delete 31. The method of claim 30, The passivation gas is C ₂ H ₄ , CH ₄ , C ₂ H ₂ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₆ , C ₄ H ₈ , C ₄ H ₁₀ , C ₅ H ₈ , C ₅ H ₁₀ , C ₆ H ₆ , C ₆ H ₁₀ and C ₆ H ₁₂ . The method of claim 30 or 32, Wherein said processing gas further comprises helium. delete delete

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