Etching gas composition comprising hexafluoropropylene oxide and plasma etching method using same
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-05
- Publication Date
- 2026-08-13
Smart Images
Figure KR2026000169_13082026_PF_FP_ABST
Abstract
Description
Etching gas composition comprising hexafluoropropylene oxide and plasma etching method using the same
[0001] The present invention relates to an etching gas composition comprising hexafluoropropylene oxide and a plasma etching method using the same.
[0002] Perfluorocarbons (PFCs), such as CF4, C2F6, and c-C4F8, are primarily used for etching materials like SiO2 or Si3N4. However, PFCs are substances that have a negative impact on global warming due to their high Global Warming Potential (GWP). Furthermore, as chip density continues to increase, the number of process iterations gradually rises, leading to a corresponding increase in both PFC usage and emissions. According to the 2023 National Greenhouse Gas Inventory Report, PFC usage in the semiconductor and display manufacturing industries has been continuously increasing since 2009. Additionally, the statement from the 25th World Semiconductor Council (WSC) meeting indicates that the amount of PFCs emitted by global semiconductor manufacturers has been on an annual upward trend since 2012. Consequently, the semiconductor industry is making various attempts to reduce PFC emissions.
[0003] As part of efforts to reduce PFC emissions, research on etching processes using materials with a lower GWP than PFCs is actively underway. Notably, numerous papers and patents have been reported regarding etching technologies utilizing low-GWP materials such as HFE-347mcc3, HFE-347mmy, HFIP, and heptafluoroisopropyl trifluoromethyl ketone. Materials with low GWP, like these, are characterized by containing multiple bonds or groups such as O and H in their molecular structures. Their low GWP is due to the fact that they readily decompose by reacting with hydroxyl radicals (-OH) in the atmosphere. This reaction can also occur in epoxide functional groups containing O. This is because triangular ring-shaped functional groups can decompose and combine with H to easily form OH functional groups. Therefore, fluoro-epoxide-based materials are also expected to replace PFCs in etching processes.
[0004] One objective of the present invention is to provide an etching gas composition comprising hexafluoropropylene oxide that can etch dielectrics by replacing PFCs.
[0005] Another objective of the present invention is to provide a plasma etching method using the etching gas composition.
[0006] To achieve the above objective, the present invention provides an etching gas composition supplied to an etching chamber to generate plasma, comprising: a fluorocarbon gas containing hexafluoropropylene oxide (C3F6O); and an inert gas.
[0007] In addition, the present invention provides a plasma etching method comprising the step of plasma etching a target by providing a fluorocarbon gas containing hexafluoropropylene oxide and an inert gas to a plasma chamber in which the target is placed.
[0008] According to the present invention, the etching gas composition of the present invention has a very low global warming potential compared to PFCs, so it can reduce greenhouse gas emissions.
[0009] In addition, the plasma etching method of the present invention can provide optimal conditions for the etching selectivity ratio of silicon nitride and silicon oxide with respect to a mask or Si substrate.
[0010] FIG. 1 is a schematic diagram of an inductively coupled plasma etching chamber for performing a plasma etching method according to an embodiment of the present invention.
[0011] Figure 2 shows the etching rates of SiO2, Si3N4, Si, and ACL according to the Ar / (HFPO+Ar) ratio in an HFPO / Ar plasma.
[0012] Figure 3 shows the etching selectivity of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to the Ar / (HFPO+Ar) ratio in an HFPO / Ar plasma.
[0013] Figure 4 shows the etching rates of SiO2, Si3N4, Si, and ACL as a function of source power in an HFPO / Ar plasma.
[0014] Figure 5 is a graph showing the etching selectivity ratios of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to the change in source power in an HFPO / Ar plasma.
[0015] Figure 6 is a graph showing the etching rates of SiO2, Si3N4, Si, and ACL as a function of bias voltage in an HFPO / Ar plasma.
[0016] Figure 7 is a graph showing the etching selectivity ratios of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to the change in bias voltage in an HFPO / Ar plasma.
[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Since the present invention is susceptible to various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing. In the attached drawings, the dimensions of the structures are shown enlarged compared to the actual dimensions for the clarity of the present invention.
[0018] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.
[0019] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.
[0020] Meanwhile, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.
[0021] The etching gas composition of the present invention is an etching gas composition supplied to an etching chamber to generate plasma, and may include a fluorocarbon gas containing hexafluoropropylene oxide (C3F6O; HFPO); and an inert gas.
[0022] In one embodiment, the inert gas may be argon (Ar), but is not limited thereto. The inert gas may be a gas commonly used in plasma etching.
[0023] In one embodiment, the fraction of inert gas in the etching gas composition may be 66 to 90%. For example, the fraction of inert gas may be 76 to 87%. If the fraction of inert gas is less than 66% or greater than 90%, the etching rate may decrease, and the etching process time may increase.
[0024] The present invention describes a plasma etching method using the above-described etching gas composition. The plasma etching method may include the step of plasma etching the etching target by providing a fluorinated carbon gas containing hexafluoropropylene oxide (C3F6O) and an inert gas to a plasma chamber in which the etching target is placed.
[0025] In one embodiment, the source power supplied to the fluorocarbon gas and inert gas containing hexafluoropropylene oxide may be 200 to 500 W, but is not limited thereto. Since the etching rate of SiO2, Si3N4, Si, and ACL increases depending on the source power, the source power can be adjusted to match the desired etching rate.
[0026] In one embodiment, the bias voltage applied to the back surface of the etching target may be -400 to -1000 V, but is not limited thereto.
[0027] In one embodiment, the etching target may include, but is not limited to, one or more selected from the group consisting of silicon oxide with an ACL (Amorphous Carbon Layer) mask layer formed thereon, silicon nitride with an ACL mask layer formed thereon, silicon oxide with a PR (photoresist) mask layer formed thereon, silicon nitride with a PR mask layer formed thereon, silicon oxide formed on a Si substrate, and silicon nitride formed on a Si substrate. The etching target may include a commonly used silicon-based dielectric.
[0028] In one embodiment, the etching ratio of the ACL or Si to the silicon oxide or silicon nitride may be 0.5 to 4.5, 1.5 to 4.5, or 2.0 to 4.0, but is not limited thereto.
[0029] Hereinafter, the present invention will be described in detail with reference to examples to aid in understanding. However, the following examples are merely illustrative of the content of the present invention and the scope of the present invention is not limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those with average knowledge in the art.
[0030] <Examples 1 to 5 and Comparative Examples 1 to 3>
[0031] FIG. 1 is a schematic diagram of an inductively coupled plasma etching chamber for performing a plasma etching method according to an embodiment of the present invention. Hexafluoropropylene oxide (C3F6O, hereinafter HFPO) was used. To introduce HFPO into the chamber, a mass flow controller (MFC) was used to control the HFPO to a desired flow rate and introduce it into the chamber.
[0032] To verify the etching characteristics of SiO2, Si3N4, Si, and ACL according to the Ar / (HFPO+Ar) ratio in an HFPO / Ar plasma, the ratios of HFPO and Ar were adjusted to the compositions shown in Table 1 below. The etching targets were a SiO2 thin film, a Si3N4 thin film, a Si substrate, and an ACL mask layer, and the source power was set to approximately 250 W, the bias voltage to approximately -600 V, the gas pressure to approximately 10 mTorr, and the electrode temperature to approximately 15 ℃.
[0033] C5F 10 O(sccm)Ar(sccm)Ar Fraction (%) Comparative Example 1 3000 0.0 Comparative Example 2 2010 33.3 Example 1 1020 66.7 Example 2 723 76.7 Example 3 624 80.0 Example 4 525 83.3 Example 5 426 86.7 Comparative Example 3 129 96.7
[0034] <Examples 6 to 9>
[0035] To verify the etching characteristics of SiO2, Si3N4, Si, and ACL according to source power in HFPO / Ar plasma, the source power was adjusted according to Table 2 below, and etching was performed in the same manner as in Example 3 above.
[0036] Source Power (W) Example 6200 Example 3250 Example 7300 Example 8400 Example 9500
[0037] <Examples 10 to 12>
[0038] To verify the etching characteristics of SiO2, Si3N4, Si, and ACL according to the bias voltage in the HFPO / Ar plasma, the bias voltage was adjusted according to Table 3 below, and etching was performed in the same manner as in Example 3 above.
[0039] Bias voltage (V) Example 10-400 Example 3-600 Example 11-800 Example 12-1000
[0040] <Experimental Example 1>
[0041] Figure 2 shows the etching rates of SiO2 thin films, Si3N4 thin films, Si substrates, and ACL mask layers according to the Ar / (HFPO+Ar) ratio in an HFPO / Ar plasma. In Figure 2, when the Ar / (HFPO+Ar) ratio was approximately 0 to 66.7%, HFPO was not sufficiently dissociated, so the plasma density hardly changed, and consequently, it was determined that all etching rates remained constant and hardly changed. Subsequently, when the Ar / (HFPO+Ar) ratio increased from approximately 66.7% to 80%, the etching rates of all specimens increased, and when the Ar / (HFPO+Ar) ratio increased from 80% to 96.7%, the etching rates of all specimens decreased.
[0042] In Figure 2, at an Ar / (HFPO+Ar) ratio of 0 to 66.7%, HFPO was not sufficiently decomposed, so the plasma density hardly changed, and consequently, it was determined that the etching rate of all specimens hardly changed. Subsequently, when the Ar / (HFPO+Ar) ratio increased from 66.7% to 80%, the decomposition of HFPO increased, leading to an increase in plasma density and the generation of a large amount of ions or radicals involved in etching, such as F or CF3, which was determined to have increased the etching rate of all specimens. Subsequently, when the Ar / (HFPO+Ar) ratio increased from 80% to 96.7%, it was determined that the etching rate of all specimens decreased because the flow rate of HFPO, which can supply ions or radicals such as F or CF3, decreased.
[0043] Figure 3 is a graph showing the etching selectivity ratios of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to the Ar / (HFPO+Ar) ratio, based on the etching rate results of Figure 2 in HFPO / Ar plasma. In Figure 3, the etching selectivity ratio of SiO2 / Si3N4 remained almost constant at 1 even as the Ar / (HFPO+Ar) ratio changed. This was determined to be because the etching rate trends of SiO2 and Si3N4 according to the Ar / (HFPO+Ar) ratio were nearly similar. The etching selectivity ratio of Si3N4 / ACL remained almost constant at a value of approximately 2.6 to 2.8 across Ar / (HFPO+Ar) ratios ranging from 0% to 76.7%. However, when the Ar / (HFPO+Ar) ratio increased from 76.7% to 86.7%, the Si3N4 / ACL etching selectivity increased, and when the Ar / (HFPO+Ar) ratio increased from 86.7% to 96.7%, the Si3N4 / ACL etching selectivity decreased.
[0044] It was determined that the etching rates of Si3N4 and Si remained almost constant at an Ar / (HFPO+Ar) ratio of 0% to 66.7%. At an Ar / (HFPO+Ar) ratio of 66.7% to 76.7%, the increase in etching rates of Si3N4 and Si was similar, so the Si3N4 / ACL etching selectivity remained almost constant. However, it was determined that when the Ar / (HFPO+Ar) ratio increased from 76.7% to 86.7%, the etching rate of Si3N4 increased faster than that of Si, and thus the Si3N4 / ACL etching selectivity also increased. Subsequently, when the Ar / (HFPO+Ar) ratio increased from 86.7% to 96.7%, the etching rate of Si3N4 decreased faster than that of Si, and thus the Si3N4 / ACL etching selectivity decreased.
[0045] The Si3N4 / Si etch selectivity remained almost constant at an Ar / (HFPO+Ar) ratio of 0% to 66.7%. Subsequently, as the Ar / (HFPO+Ar) ratio increased from 66.7% to 83.3%, the Si3N4 / Si etch selectivity increased, reaching a maximum at 83.3%. As the Ar / (HFPO+Ar) ratio increased from 83.3% to 96.7%, the Si3N4 / Si etch selectivity decreased.
[0046] It was determined that when the Ar / (HFPO+Ar) ratio increased from 66.7% to 83.3%, the Si3N4 etching rate increased faster than Si, and thus the Si3N4 / Si etching selectivity increased. Subsequently, when the Ar / (HFPO+Ar) ratio increased from 83.3% to 96.7%, although the change in Si etching rate was not significant, the Si3N4 etching rate decreased significantly, so it was determined that the Si3N4 / Si etching selectivity decreased.
[0047] <Experimental Example 2>
[0048] Figure 4 shows the etching rates of SiO2, Si3N4, Si, and ACL according to source power in an HFPO / Ar plasma. As the source power increased from approximately 200 W to 500 W, the etching rates of SiO2, Si3N4, Si, and ACL all increased. This is because as the source power increases, the power applied to the plasma increases, and consequently, the plasma density increases.
[0049] Figure 5 is a graph showing the etching selectivity ratios of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to changes in source power, based on the results of Figure 4. Even as the source power increased, the change in the SiO2 / Si3N4 etching selectivity ratio was minimal. However, the etching selectivity ratios of Si3N4 / ACL and Si3N4 / Si decreased as the source power increased. It was determined that this was because the increase in the etching rate of Si or ACL was greater than the increase in the etching rate of Si3N4 as the source power increased.
[0050] <Experimental Example 3>
[0051] Figure 6 is a graph showing the etching of SiO2, Si3N4, Si, and ACL according to changes in bias voltage in an HFPO / Ar plasma. In Figure 6, when the bias voltage increased from approximately -400 V to -1000 V, the etching rate of SiO2, Si3N4, Si, and ACL increased. This is because the etching rate increased in all thin films as the ion energy increased as the bias voltage increased.
[0052] Figure 7 is a graph showing the etching selectivity of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si according to changes in bias voltage, based on the results of Figure 6. As the bias voltage increased, there was no significant change in the etching selectivity of SiO2 / Si3N4, Si3N4 / ACL, and Si3N4 / Si. Since the HFPO / Ar plasma shows almost no change in etching rate with respect to changes in bias voltage, it was determined that the wide bias voltage setting range is advantageous for securing process conditions.
[0053] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as set forth in the following claims.
Claims
1. An etching gas composition supplied to an etching chamber to generate plasma, wherein Fluorocarbon gas containing hexafluoropropylene oxide (C3F6O); and Etching gas composition comprising an inert gas.
2. In Paragraph 1, An etching gas composition in which the above inert gas is argon (Ar).
3. In Paragraph 2, An etching gas composition in which the fraction of inert gas in the above etching gas composition is 66 to 90 percent.
4. In Paragraph 2, An etching gas composition in which the fraction of inert gas in the above etching gas composition is 76 to 87%.
5. A plasma etching method comprising the step of plasma etching a target by providing a fluorinated carbon gas containing hexafluoropropylene oxide and an inert gas to a plasma chamber in which the target is placed.
6. In Paragraph 5, A plasma etching method in which the source power supplied to the fluorocarbon gas and inert gas containing the hexafluoropropylene oxide is 200 to 500 W.
7. In Paragraph 5, A plasma etching method in which the bias voltage applied to the back surface of the etching target is -400 to -1000 V.
8. In Paragraph 5, A plasma etching method comprising one or more selected from the group consisting of silicon oxide with an ACL (Amorphous Carbon Layer) mask layer formed thereon, silicon nitride with an ACL mask layer formed thereon, silicon oxide with a PR (photoresist) mask layer formed thereon, silicon nitride with a PR mask layer formed thereon, silicon oxide formed on a Si substrate, and silicon nitride formed on a Si substrate.
9. In Paragraph 8, A plasma etching method in which the etching ratio of the ACL or Si to the silicon oxide or silicon nitride is 0.5 to 4.5.