WO2024009815A1 - Substrate processing method - Google Patents

Abstract

A substrate processing method according to the present invention comprises: a step in which a substrate that comprises a silicon-containing film and a mask that is superposed on the silicon-containing film is carried into a chamber; and a step in which the silicon-containing film is etched by generating a plasma from a processing gas that contains a COF₂ gas and a hydrogen-containing gas. With respect to this substrate processing method, the flow rate of the hydrogen-containing gas relative to the total flow rate of the processing gas is not less than 13% by volume but less than 50% by volume in terms of hydrogen gas.

Description

Substrate processing method

The present disclosure relates to a substrate processing method.

Currently, in the manufacturing process of semiconductor devices, gases such as CF ₄ (perfluoromethane) gas and c-C ₄ F ₈ (perfluorocyclobutane) gas are used for dry etching, chamber cleaning, etc. Is going. For example, Patent Document 1 listed below discloses that plasma etching is performed using CF ₄ gas, C ₄ F ₈ gas, or the like. Many of the gases used in these semiconductor manufacturing processes are considered to be greenhouse gases that cause global warming, including _CO2 (carbon dioxide), which has the ability to accelerate global warming. Contains gases with a high Global Warming Potential (GWP).

JP2008-28022A

In this disclosure, in order to suppress global warming, we propose replacing various gases used in various semiconductor manufacturing processes with gases that have a low greenhouse effect.

A substrate processing method according to one aspect of the present disclosure includes a step of transporting a substrate including a silicon-containing film and a mask stacked on the silicon-containing film into a chamber, and a COF ₂ gas and a hydrogen-containing gas. a step of etching the silicon-containing film by generating plasma from a processing gas containing the hydrogen-containing gas, and the flow rate of the hydrogen-containing gas relative to the total flow rate of the processing gas is 13% by volume in terms of hydrogen gas. The content is less than 50% by volume.

By using the substrate processing method using a gas with a low greenhouse effect proposed in this disclosure in various semiconductor manufacturing processes, it is possible to suppress global warming while maintaining the performance required in the semiconductor manufacturing process. can.

FIG. 1 is a cross-sectional view showing an example of a substrate. FIG. 2 is an explanatory diagram for explaining the flow of the substrate processing method according to the first embodiment of the present disclosure. FIG. 3 is a diagram showing the results of the etching rate of various layers with respect to the flow rate ratio of hydrogen gas. FIG. 4 is a cross-sectional view showing an example of the substrate. FIG. 5 is a cross-sectional view showing an example of the substrate. FIG. 6 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

Hereinafter, embodiments of the film forming method disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed film forming method is not limited by this embodiment. Further, in this specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals and redundant explanation will be omitted.

In addition, the drawings referred to in the following explanation are drawings for explaining one embodiment of the present disclosure and promoting understanding thereof, and for the sake of clarity, the shapes, dimensions, ratios, etc. shown in the drawings are not actual. It may be different. Further, the configuration shown in the drawings can be modified in design as appropriate with reference to the following explanation and known techniques.

In recent years, developed countries such as Japan have been required to reduce emissions of gases with a high greenhouse effect, such as CO ₂ gas, as a measure against global warming. Currently, in the manufacturing process of semiconductor devices, as described above, gases such as CF ₄ gas and c-C ₄ F ₈ gas are used for dry etching, chamber interior cleaning, and the like. Many of the gases used in these semiconductor manufacturing processes are considered to be greenhouse gases that cause global warming, and include gases with high GWP. Therefore, in the future, it will be important to suppress the emission of such gases that have a high greenhouse effect in semiconductor manufacturing processes. Specifically, CF ₄ gas has a GWP of 6630, and c-C ₄ F ₈ gas has a GWP of 9540, and the higher the GWP, the higher the greenhouse effect.

Therefore, in the present disclosure, in order to suppress global warming, various gases used in various semiconductor manufacturing processes are replaced with gases with a low greenhouse effect with a GWP of 1000 or less, preferably 100 or less. think about. Hereinafter, details of embodiments of the present disclosure will be sequentially described.

<First embodiment>
First, as a first embodiment of the present disclosure, we will consider replacing a gas with a low greenhouse effect in a dry etching process for forming a wiring layer of a logic circuit, which is one of the semiconductor device manufacturing processes.

Hereinafter, the etching process of this embodiment will be explained with reference to FIG. FIG. 1 is a cross-sectional view showing an example of a substrate W processed in this embodiment. In this embodiment, for example, an etching process is performed on a substrate W as shown in FIG. Specifically, as shown in FIG. 1, the substrate W includes a base layer 210 and a film laminated on the base layer 210 and containing silicon (Si) (silicon-containing film), and is an etching target. The processing target layer 200 has a mask 220 laminated on the processing target layer 200.

The base layer 210 can be, for example, a metal film or a conductive layer such as a silicon film. Furthermore, the metal film can be made of, for example, tungsten (W), aluminum (Al), copper (Cu), or the like. Furthermore, the layer 200 to be etched can be a silicon oxide film (SiO ₂ ) or a low dielectric constant (Low-k) film. Further, the low-k film can be, for example, a SiOC film (carbon-containing silicon oxide film), a silicon carbonitride film (SiCN), a SiOCH (hydrocarbon-containing silicon oxide film), or a combination thereof.

Furthermore, in this embodiment, the base layer 210 is not limited to the above-mentioned conductor layer. For example, it may be desired that the base layer 210 has a high selectivity with respect to the layer to be processed 200 and that there is little loss in the base layer 210. More specifically, for example, when forming a Self-Aligned Contact (SAC) structure, the base layer 210 is a silicon nitride film (SiN) or the like, and the processed layer 200 is a silicon oxide film or the like. . Further, when forming a via structure, the base layer 210 is a silicon carbide film (SiC), a silicon carbonitride film, etc., and the layer to be processed 200 is a silicon oxide film, a low-k film, etc. becomes.

The mask 220 has a desired opening pattern and functions as a protective film when etching a desired portion of the layer 200 to be processed. In this embodiment, mask 220 includes at least one of carbon and metal. Specifically, in this embodiment, the mask 220 may be a carbon-containing mask or a metal-containing mask. Further, in this embodiment, the carbon-containing mask may be spin-on carbon (SOC), tungsten carbide, amorphous carbon, boron carbide, etc., and combinations thereof. Further, in this embodiment, the metal-containing mask may be a titanium nitride film (TiN), a tungsten carbide film (WC), or the like.

Hereinafter, a substrate processing method according to the present embodiment will be described in which a gas with a low greenhouse effect is used as a substitute gas in etching such a substrate W.

The flow of the substrate processing method according to this embodiment will be explained with reference to FIG. 2. FIG. 2 is an explanatory diagram for explaining the flow of the substrate processing method according to the present embodiment. As shown in FIG. 2, the substrate processing method according to the embodiment of the present disclosure includes the step (S1) of transporting the substrate W described above into the plasma processing apparatus (chamber), and the step (S1) of transporting the substrate W described above into the plasma processing apparatus (chamber), and plasma processing from the processing gas described below. and etching the layer to be processed 200 (S2). Specifically, in this embodiment, for example, a trench is formed by etching the layer to be processed 200 using a mask 220 having a desired opening pattern.

The processing gas for the etching process according to this embodiment includes COF ₂ (carbonyl fluoride) gas and hydrogen-containing gas.

COF ₂ gas has a lower global warming effect than, for example, CF ₄ gas (GWP: 6630), which has been used in a dry etching process for forming wiring layers of logic circuits. Therefore, in this embodiment, global warming can be suppressed by using COF ₂ gas, which has a low greenhouse effect.

Further, the hydrogen-containing gas is one type of gas selected from the group consisting of hydrogen (H ₂ ) gas, hydrogen fluoride (HF) gas, and hydrofluoroolefin gas, or multiple types of gas selected from these. It may also be a combination of gases. In addition, hydrofluoroolefin gases include C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetrafluoropropene) gas, and C ₄ H ₂ F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, or a combination thereof. For example, C ₂ H ₂ F ₂ gas and C ₃ H ₂ F ₄ gas have a GWP of 1 or less, and C ₄ H ₂ F ₆ gas has a GWP of 7 or less. That is, the above-mentioned hydrogen-containing gas has a low greenhouse effect, and is lower than that of CHF ₃ (trifluoromethane) (GWP: 12400), etc., which has been used in the dry etching process for forming wiring layers of logic circuits. Therefore, in this embodiment, global warming can be suppressed by using the hydrogen-containing gas that has a low greenhouse effect as described above.

Furthermore, in this embodiment, the hydrogen-containing gas is C ₃ HF ₅ (pentafluoropropene) gas, C ₄ H ₃ F ₅ (3,3,4,4,4-pentafluoro-1-butene, etc.) gas. , C ₄ HF ₅ (1,1,2,3,4-pentafluorobuta-1,3-diene) gas, or the like. Since these gases also have a low greenhouse effect, global warming can be suppressed by using hydrogen-containing gases that have a low greenhouse effect.

Furthermore, the processing gas for the etching process according to this embodiment may contain an inert gas. The inert gas can be a noble gas such as argon (Ar), helium (He), nitrogen ( _N2 ) gas, or a combination thereof.

In this embodiment, for example, the layer to be processed 200 of the substrate W is etched by plasma of a processing gas containing COF ₂ gas and hydrogen-containing gas using the mask 220 described above using a plasma processing apparatus described later. do. In this embodiment, the flow rate of the hydrogen-containing gas relative to the total flow rate of the processing gas (or the processing gas excluding the inert gas if it contains an inert gas) is 13% in terms of hydrogen (H ₂ ) gas. % by volume or more and less than 50% by volume. In the etching process according to this embodiment, the hydrogen-containing gas functions to extract oxygen contained in the COF ₄ gas in the form of OH. In this embodiment, by using a hydrogen-containing gas having such a function, COF ₄ gas can function as an etching gas at the same level as conventionally used gases such as CF ₄ gas. . Note that in this embodiment, the flow rate of the hydrogen-containing gas is defined as the volumetric amount of the hydrogen gas converted by converting the hydrogen contained in the hydrogen-containing gas into hydrogen gas.

Here, with reference to FIG. 3, the etching rates of the photoresist, silicon oxide film, and silicon nitride film by the etching process according to this embodiment will be discussed. FIG. 3 is a diagram showing the results of the etching rate of various layers with respect to the flow rate ratio of hydrogen gas. In detail, the horizontal axis in FIG. 3 shows the ratio of hydrogen gas to the total flow rate of the processing gas (COF ₂ ) excluding inert gas, and the vertical axis shows the ratio of the photoresist (PR), silicon oxide film, etc. , each etching rate (nm/min) of the silicon nitride film is shown. Here, COF ₂ gas, hydrogen gas, and nitrogen gas were used as processing gases, and the photoresist, silicon oxide film, and silicon nitride were Etching was performed on three of the films.

From the results shown in Figure 3, even when COF ₂ gas is used as the processing gas, the silicon oxide film and silicon nitride film are etched at the same etching rate as when CF ₄ gas is used as the processing gas. I found out that it will happen. That is, according to the present embodiment, even when using COF ₂ gas having a low greenhouse effect, it is possible to obtain process performance equivalent to that of CF ₄ gas used so far in the process.

In addition, as shown in FIG. 3, by setting the volume ratio of the hydrogen gas flow rate to the total flow rate of the processing gas to be 13% to 50% (range indicated by the arrow in FIG. 3), the silicon oxide film is It was found that the resist was selectively etched.

As described above, global warming can be suppressed by performing etching using the processing gas with low greenhouse effect according to this embodiment in the dry etching process for forming the wiring layer of the logic circuit. . Furthermore, according to the present embodiment, even when such a gas with a low greenhouse effect is used, it is possible to obtain process performance equivalent to that of the processing gas used so far in the process.

Further, in the dry etching process for forming the wiring layer of the logic circuit according to another embodiment, for example, COF ₂ gas, CF (fluorocarbon)-based gas, and inert gas may be used as the processing gas. good. In this other embodiment, the CF-based gas is C ₃ F ₆ (hexafluoropropene) gas, C ₄ F ₈ (octafluoro-1-butene, octafluoro-2-butene) gas, linear C ₄ It can be F ₈ O gas or a combination thereof. Since these gases also have a low greenhouse effect, global warming can be suppressed by using such CF-based gases that have a low greenhouse effect.

In addition, in the dry etching process for forming the wiring layer of the logic circuit according to another embodiment, for example, COF ₂ gas, CHF (hydrofluorocarbon)-based gas, and inert gas are used as the processing gas. Good too. In such other embodiments, the CHF-based gas can be CH ₂ F ₂ (difluoromethane) gas, CH ₃ F (fluoromethane) gas, or a combination thereof. For example, CH ₂ F ₂ gas has a GWP of 677, CH ₃ F gas has a GWP of 116, and both have a GWP of 1000 or less. Since these gases also have a low greenhouse effect, global warming can be suppressed by using CHF gases that have a low greenhouse effect. Further, as the processing gas for the etching step, hydrogen fluoride (HF) gas may be used instead of or together with the CHF-based gas.

<Second embodiment>
Next, as a second embodiment of the present disclosure, consideration will be given to replacing a gas with a low greenhouse effect in a dry etching process for forming a DRAM (Dynamic Random Access Memory) device.

Hereinafter, the substrate processing method of this embodiment will be explained with reference to FIG. 4. FIG. 4 is a cross-sectional view showing an example of a substrate W processed in this embodiment. In this embodiment, the substrate processing method includes performing an etching process on a substrate W as shown in FIG. 4, for example. Specifically, as shown in FIG. 4, the substrate W includes a base layer 212, a layer laminated on the base layer 212, a layer 200 to be etched, and a layer laminated on the layer 200. It has a mask 220. Each layer of the substrate W will be described below, but descriptions of points common to the above-described embodiments will be omitted here.

In this embodiment, the base layer 212 can be, for example, a metal film, a silicon film, etc., and is not particularly limited.

Furthermore, in this embodiment, the layer to be processed 200 may include one oxide film (for example, a silicon oxide film) and one or more nitride films (for example, a silicon nitride film). In this embodiment, for example, as shown in FIG. 4, the layer to be processed 200 includes two silicon nitride films 204 and a silicon oxide film 202 sandwiched between the two silicon nitride films 204. For example, the silicon oxide film 202 has a thickness of approximately 800 nm to 1200 nm, and the silicon nitride film 204 has a thickness of approximately 300 nm to 400 nm.

In this embodiment, a trench is formed by etching the layer to be processed 200 using a mask 220 having a desired opening pattern. The trench may, for example, be generally cylindrical with a depth of about 1 μm to 3 μm. Further, the generally cylindrical shape may have a diameter of, for example, about 20 nm to 50 nm. For example, a capacitor memory cell can be formed inside such a substantially cylindrical trench.

Hereinafter, in etching such a substrate W, an etching process included in the substrate processing method according to the present embodiment, which uses a gas with a low greenhouse effect as a substitute gas, will be described. In this embodiment, for example, a trench is formed by etching the layer to be processed 200 using a mask 220 having a desired opening pattern.

The processing gas for the etching process according to this embodiment includes a CF (fluorocarbon)-based gas and an inert gas. The CF-based gas can be C ₃ F ₆ (hexafluoropropene) gas, C ₄ F ₈ (octafluoro-1-butene, octafluoro-2-butene) gas, or a combination thereof. For example, C ₃ F ₆ gas has a GWP of 1 or less, and C ₄ F ₆ (hexafluoro-1,3-butadiene) gas (GWP: 290 ), etc., have a lower GWP. Therefore, in this embodiment, global warming can be suppressed by using the hydrogen-containing gas that has a low greenhouse effect as described above.

Additionally, the inert gas can be a rare gas such as argon or helium, nitrogen gas, or a combination thereof.

Furthermore, in this embodiment, the processing gas may contain oxygen (O ₂ ) gas.

As described above, global warming can be suppressed by performing etching using a process gas with a low greenhouse effect according to this embodiment in the dry etching process for forming a DRAM device. Furthermore, according to the present embodiment, even when such a gas with a low greenhouse effect is used, it is possible to obtain process performance equivalent to that of the processing gas used so far in the process.

<Third embodiment>
Next, as a third embodiment of the present disclosure, consideration will be given to substituting a gas with a low greenhouse effect in the dry etching process for forming a vertical NAND flash memory device. Note that the vertical NAND structure is also referred to as a VNAND or 3D-NAND structure.

Hereinafter, the substrate processing method of this embodiment will be explained with reference to FIG. FIG. 5 is a cross-sectional view showing an example of a substrate W processed in this embodiment. In this embodiment, the substrate processing method includes performing an etching process on a substrate W as shown in FIG. 5, for example. Specifically, as shown in FIG. 5, the substrate W includes a base layer 212, a layer laminated on the base layer 212, a layer 200 to be etched, and a layer laminated on the layer 200 to be etched. It has a mask 220. Each layer of the substrate W will be described below, but descriptions of points common to the above-described embodiments will be omitted here.

In this embodiment, the base layer 212 can be, for example, a metal film, a silicon film, etc., and is not particularly limited.

In this embodiment, the layer to be processed 200 has a laminated structure consisting of one oxide film 202 (for example, silicon oxide film) and one nitride film 204 (for example, silicon nitride film), as shown in FIG. It may contain more than one. Alternatively, the layer to be processed 200 may include a plurality of laminated structures each consisting of one oxide film (for example, a silicon oxide film) and one silicon film (for example, a polysilicon film). Furthermore, the layer to be treated 200 may include at least about 20 of the above laminated structures, preferably about 40, more preferably about 60, and even more preferably about 70. Note that in FIG. 5, for convenience, the layer to be processed 200 is illustrated as having five of the above-mentioned laminate structures, but in this embodiment, the layer to be processed 200 includes at least about 20 of the above-mentioned laminate structures. The number is not limited as long as it includes the following.

In this embodiment, a trench is formed by etching the layer to be processed 200 using a mask 220 having a desired opening pattern. The trench has a depth of approximately 2 μm to 6 μm, for example. Further, the trench may have a width of about 50 nm to 150 nm, for example.

Hereinafter, in etching such a substrate W, an etching process included in the substrate processing method according to the present embodiment, which uses a gas with a low greenhouse effect as a substitute gas, will be described. In this embodiment, for example, a trench is formed by etching the layer to be processed 200 using a mask 220 having a desired opening pattern.

The processing gas for the etching process according to this embodiment includes a CF-based gas, a hydrogen-containing gas, and an oxygen gas. The CF-based gas can be C ₃ F ₆ (hexafluoropropene) gas, C ₄ F ₈ (octafluoro-1-butene, octafluoro-2-butene) gas, or a combination thereof. As explained above, for example, C ₃ F ₆ gas has a GWP of 1 or less. Furthermore, C ₃ F ₆ gas and the like are more expensive than c-C ₄ F ₈ (perfluorocyclobutane) gas (GWP: 9540), which has been conventionally used in the dry etching process for forming vertical NAND flash memory devices. , has a low GWP. Furthermore, C ₃ F ₆ gas etc. has a lower GWP than the conventionally used NF ₃ (nitrogen trifluoride) gas (GWP: 16100) and SF ₆ (sulfur hexafluoride) gas (GWP: 23500). have. Therefore, in this embodiment, global warming can be suppressed by using the CF-based gas that has a low greenhouse effect as described above.

Further, the hydrogen-containing gas may be one type of gas selected from the group consisting of hydrogen gas, hydrogen fluoride gas, and hydrofluoroolefin gas, or a combination of multiple types of gases selected from these. good. In addition, hydrofluoroolefin gases include C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetrafluoropropene) gas, and C ₄ H ₂ F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, or a combination thereof. As explained above, these gases also have a low greenhouse effect; for example, C ₃ H ₂ F ₄ gas has a GWP of 1 or less, and C ₄ H ₂ F ₆ gas has a GWP of 7 or less. be. Therefore, in this embodiment, global warming can be suppressed by using the hydrogen-containing gas that has a low greenhouse effect as described above.

As described above, global warming can be suppressed by performing etching using a processing gas with a low greenhouse effect according to this embodiment in the dry etching process for forming a vertical NAND type device. Furthermore, according to the present embodiment, even when such a gas with a low greenhouse effect is used, it is possible to obtain process performance equivalent to that of the processing gas used so far in the process.

<Fourth embodiment>
Semiconductor device manufacturing processes form various semiconductor devices such as microprocessors, logic circuits, and memory devices. Such semiconductor devices may be manufactured by processes that include patterning techniques to create various types of masks. Specifically, in some of these processes, a layer containing a silicon oxide film, a silicon nitride film, a silicon film, or the like is etched. An etching process using a gas with a low greenhouse effect as an alternative gas will be described below.

(silicon oxide film)
In this embodiment, the processing gas for the etching process for the silicon oxide film includes a CF-based gas, oxygen gas, and an inert gas. The CF-based gas can be C ₃ F ₆ (hexafluoropropene) gas, C ₄ F ₈ (octafluoro-1-butene, octafluoro-2-butene) gas, or a combination thereof. As explained above, for example, C ₃ F ₆ gas has a GWP of 1 or less, and CF ₄ gas (GWP: 6630) and CHF ₃ (trifluoromethane) gas, which have been used in the etching process for silicon oxide films, are (GWP: 12400), etc., has a lower GWP. Therefore, in this embodiment, global warming can be suppressed by using the CF-based gas that has a low greenhouse effect as described above.

Additionally, the inert gas can be a rare gas such as argon or helium, nitrogen gas, or a combination thereof.

Further, in this embodiment, the processing gas for the etching process for the silicon oxide film may include a CF-based gas and a CHF (hydrofluorocarbon)-based gas. The CF-based gas is COF ₂ gas, C ₄ F ₈ O (pentafluoroethyl trifluorovinyl ether) gas, CF ₃ COF (1,2,2,2-tetrafluoroethane-1-one) gas, or any of these gases. It can be a combination. Furthermore, examples of the CHF-based gas include CHF ₂ COF (difluoroacetic acid fluoride) gas. Therefore, in this embodiment, global warming can be suppressed by using the above-mentioned CF-based gas and CHF-based gas that have a low greenhouse effect. Furthermore, in the processing gas for the above-mentioned etching process, hydrogen fluoride (HF) gas may be used instead of the CHF-based gas or together with the CHF-based gas.

(silicon nitride film)
In this embodiment, the processing gas for the etching process for the silicon nitride film includes a hydrogen-containing gas, an oxygen gas, and an inert gas. The hydrogen-containing gas can be one type of gas selected from the group consisting of hydrogen gas, hydrogen fluoride gas, and hydrofluoroolefin gas, or a combination of multiple types of gases selected from these. In addition, hydrofluoroolefin gases include C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetrafluoropropene) gas, and C ₄ H ₂ F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, or a combination thereof. For example, C ₃ H ₂ F ₄ gas has a GWP of 1, and C ₄ H ₂ F ₆ gas has a GWP of ₇ or less. ) gas (GWP: 116), etc., has a low GWP. Therefore, in this embodiment, global warming can be suppressed by using the hydrogen-containing gas that has a low greenhouse effect as described above.

Additionally, the inert gas can be a rare gas such as argon or helium, nitrogen gas, or a combination thereof.

(silicon film)
In this embodiment, the processing gas for the etching process for the silicon film includes a hydrogen-containing gas, an oxygen gas, and an inert gas. The hydrogen-containing gas can include hydrogen fluoride gas, hydrogen bromide (HBr) gas, and the like. For example, HBr gas has a lower GWP than NF ₃ (nitrogen trifluoride) gas (GWP: 16100), which has been used in the etching process for silicon films. Therefore, in this embodiment, global warming can be suppressed by using the hydrogen-containing gas that has a low greenhouse effect as described above.

Additionally, the inert gas can be a rare gas such as argon or helium, nitrogen gas, or a combination thereof.

As described above, in the etching process for patterning a layer containing a silicon oxide film, a silicon nitride film, a silicon film, etc., etching is performed using a processing gas with a low greenhouse effect according to this embodiment. By doing so, global warming can be suppressed. Furthermore, according to the present embodiment, even when such a gas with a low greenhouse effect is used, it is possible to obtain process performance equivalent to that of the processing gas used so far in the process.

<Fifth embodiment>
In the manufacturing process of semiconductor devices, various chambers are used to generate plasma and treat a substrate with the generated plasma. During such processing, by-products generated during the processing adhere to the inner walls of the chamber and the like, and the by-products gradually accumulate and grow into particles. Such particles can have a negative impact on stable plasma generation and substrate processing, so the chamber is dry-cleaned at regular intervals to reduce particles on the inner walls, etc. .

Specifically, in dry cleaning of such a chamber, a cleaning gas and an inert gas are supplied into the chamber, plasma is generated using the supplied gas, and the inner walls of the chamber are cleaned with the plasma. do. Conventionally used cleaning gases include, for example, NF ₃ (nitrogen trifluoride) gas (GWP: 16100), SF ₆ (sulfur hexafluoride) gas (GWP: 23500), etc. Gas has a high GWP, ie, a high greenhouse effect.

Hereinafter, in such cleaning, cleaning according to the present embodiment will be described in which a gas with a low greenhouse effect is used as an alternative gas.

In this embodiment, the cleaning gas is COF ₂ gas, HF (hydrogen fluoride) gas, fluorine (F ₂ ) gas, FNO (nitrosyl fluoride) gas, F ₃ NO (trifluoroamine oxide) gas, or It can be a combination of these. These gases have a lower greenhouse effect than NF ₃ gas (GWP 16100), SF ₆ gas (GWP 23500), etc. that have been used as cleaning gases so far. Therefore, in this embodiment, global warming can be suppressed by using a cleaning gas with a low greenhouse effect as described above.

As described above, global warming can be suppressed by dry cleaning the chamber using the cleaning gas with low greenhouse effect according to the present embodiment. Furthermore, according to the present embodiment, even when such a gas with a low greenhouse effect is used, cleaning performance equivalent to that of the cleaning gas used up to now can be obtained in the cleaning.

<Plasma processing equipment>
Next, an example of a plasma processing apparatus that can be applied to the substrate processing method according to each embodiment of the present disclosure will be described. FIG. 6 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

As shown in FIG. 6, the plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control section 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply section 20, a power supply 30, and an exhaust system 40. Further, the plasma processing apparatus 1 includes a substrate support section 11 and a gas introduction section. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10 . The gas introduction section includes a shower head 13. Substrate support 11 is arranged within plasma processing chamber 10 . The shower head 13 is arranged above the substrate support section 11 . In one embodiment, showerhead 13 forms at least a portion of the ceiling of plasma processing chamber 10 . The plasma processing chamber 10 has a plasma processing space 10s defined by a shower head 13, a side wall 10a of the plasma processing chamber 10, and a substrate support 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s, and at least one gas exhaust port for discharging gas from the plasma processing space. Plasma processing chamber 10 is grounded. The shower head 13 and the substrate support section 11 are electrically insulated from the casing of the plasma processing chamber 10.

The substrate support section 11 includes a main body section 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in plan view. The substrate W is placed on the central region 111a of the main body 111, and the ring assembly 112 is placed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. Base 1110 includes a conductive member. The conductive member of the base 1110 can function as a bottom electrode. Electrostatic chuck 1111 is placed on base 1110. Electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within ceramic member 1111a. Ceramic member 1111a has a central region 111a. In one embodiment, ceramic member 1111a also has an annular region 111b. Note that another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulation member, or may be placed on both the electrostatic chuck 1111 and the annular insulation member. Further, at least one RF/DC electrode coupled to an RF power source 31 and/or a DC (Direct Current) power source 32, which will be described later, may be arranged within the ceramic member 1111a. In this case, at least one RF/DC electrode functions as a bottom electrode. An RF/DC electrode is also referred to as a bias electrode if a bias RF signal and/or a DC signal, as described below, is supplied to at least one RF/DC electrode. Note that the conductive member of the base 1110 and at least one RF/DC electrode may function as a plurality of lower electrodes. Further, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

Ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge ring is made of a conductive or insulating material, and the cover ring is made of an insulating material.

Further, the substrate support unit 11 may include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, a channel 1110a is formed within the base 1110 and one or more heaters are disposed within the ceramic member 1111a of the electrostatic chuck 1111. Further, the substrate support section 11 may include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

The shower head 13 is configured to introduce at least one processing gas from the gas supply section 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the shower head 13, the gas introduction section may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

The gas supply section 20 may include at least one gas source 21 and at least one flow rate controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 to the showerhead 13 via a respective flow controller 22 . Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, gas supply 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one process gas.

Power supply 30 includes an RF power supply 31 coupled to plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power) to at least one bottom electrode and/or at least one top electrode. Thereby, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Accordingly, RF power source 31 may function as at least part of a plasma generation unit configured to generate a plasma from one or more process gases in plasma processing chamber 10 . Further, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated in the substrate W, and ion components in the formed plasma can be drawn into the substrate W.

In one embodiment, the RF power supply 31 includes a first RF generation section 31a and a second RF generation section 31b. The first RF generation section 31a is coupled to at least one lower electrode and/or at least one upper electrode via at least one impedance matching circuit, and generates a source RF signal (source RF power) for plasma generation. configured to generate. In one embodiment, the source RF signal has a frequency within the range of 10 MHz to 150 MHz. In one embodiment, the first RF generator 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are provided to at least one bottom electrode and/or at least one top electrode.

The second RF generating section 31b is coupled to at least one lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same or different than the frequency of the source RF signal. In one embodiment, the bias RF signal has a lower frequency than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency within the range of 100kHz to 60MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are provided to at least one bottom electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

Power source 30 may also include a DC power source 32 coupled to plasma processing chamber 10 . The DC power supply 32 includes a first DC generation section 32a and a second DC generation section 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one bottom electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one top electrode.

In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and/or to at least one upper electrode. The voltage pulse may have a pulse waveform that is rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generator for generating a sequence of voltage pulses from a DC signal is connected between the first DC generator 32a and the at least one bottom electrode. Therefore, the first DC generation section 32a and the waveform generation section constitute a voltage pulse generation section. When the second DC generation section 32b and the waveform generation section constitute a voltage pulse generation section, the voltage pulse generation section is connected to at least one upper electrode. The voltage pulse may have positive polarity or negative polarity. Further, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the first and second DC generation units 32a and 32b may be provided in addition to the RF power source 31, or the first DC generation unit 32a may be provided in place of the second RF generation unit 31b. good.

The exhaust system 40 may be connected to a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10, for example. Evacuation system 40 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various steps described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various steps described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is realized by, for example, a computer 2a. The processing unit two a1 may be configured to read a program from the storage unit two a2 and perform various control operations by executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2, and is read out from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

Note that the substrate processing method according to each embodiment of the present disclosure is not limited to using the plasma processing apparatus shown in FIG. 6, and various plasma processing apparatuses can be used depending on each manufacturing process. It is. For example, in the plasma processing apparatus shown in FIG. 6, capacitively coupled plasma (CCP) is used as a plasma source, but the embodiments of the present disclosure are not limited to this. For example, in addition to capacitively coupled plasma (CCP), inductively coupled plasma (ICP), microwave excited surface plasma (SWP), etc. may be used.

<Summary>
As described above, the substrate processing method according to the embodiment of the present disclosure includes a substrate W including a silicon-containing film (processed layer 200) and a mask 220 stacked on the silicon-containing film 200 in a chamber. and a step of etching the silicon-containing film 200 by generating plasma from a processing gas containing COF ₂ gas and a hydrogen-containing gas, and etching the silicon-containing film 200. The flow rate of the gas is 13% by volume or more and less than 50% by volume in terms of hydrogen gas. As a result, according to the substrate processing method according to the embodiment of the present disclosure, it is possible to suppress global warming and obtain process performance equivalent to that of processing gases used so far in the substrate processing method.

Further, according to an embodiment of the present disclosure, the hydrogen-containing gas may include at least one selected from the group consisting of hydrogen gas, hydrogen fluoride gas, and hydrofluoroolefin gas.

Further, according to an embodiment of the present disclosure, the hydrofluoroolefin gas is C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetra fluoropropene) gas, and C ₄ H ₂ F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas. can.

Further, according to an embodiment of the present disclosure, the processing gas may further include an inert gas, and the inert gas may include at least one of a rare gas and a nitrogen gas.

Further, according to the embodiment of the present disclosure, the silicon-containing film (processed layer 200) can include a silicon oxide film or a low-k film.

Further, according to an embodiment of the present disclosure, the Low-k film may include at least one selected from the group consisting of a SiOC film, a SiCN film, and a SiOCH film.

Further, according to an embodiment of the present disclosure, the mask 220 may include at least one of carbon and metal.

Further, according to an embodiment of the present disclosure, the carbon-containing mask may include at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

Further, according to the embodiment of the present disclosure, the etching process can be an etching process for forming a wiring layer of a logic circuit.

Further, according to an embodiment of the present disclosure, the plasma may be a capacitively coupled plasma.

<Supplement>
Although the embodiments of the present disclosure have been described above, the embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. That is, the embodiments described above may be implemented in various forms. Further, the embodiments described above may be omitted, replaced, modified, or combined in various forms without departing from the scope and spirit of the claims.

Furthermore, the effects described in this specification are merely explanatory or illustrative, and are not limiting. In other words, the technology according to the present disclosure can produce other effects that are obvious to those skilled in the art from the description of this specification, in addition to or in place of the above effects.

Note that the present disclosure can have the following configuration.
(1)
A step of carrying into the chamber a substrate including a silicon-containing film and a mask stacked on the silicon-containing film;
generating plasma from a processing gas containing COF ₂ gas and hydrogen-containing gas, and etching the silicon-containing film;
including;
The flow rate of the hydrogen-containing gas relative to the total flow rate of the processing gas is 13% by volume or more and less than 50% by volume in terms of hydrogen gas.
Substrate processing method.
(2)
The substrate processing method according to (1) above, wherein the hydrogen-containing gas includes at least one selected from the group consisting of hydrogen gas, hydrogen fluoride gas, and hydrofluoroolefin gas.
(3)
The hydrofluoroolefin gases include C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetrafluoropropene) gas, and C ₄ H ₂ Containing at least one selected from the group consisting of F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas,
The substrate processing method according to (2) above.
(4)
The substrate according to any one of (1) to (3) above, wherein the processing gas further contains an inert gas, and the inert gas contains at least one of a rare gas and a nitrogen gas. Processing method.
(5)
The substrate processing method according to any one of (1) to (4) above, wherein the silicon-containing film includes a silicon oxide film or a Low-k film.
(6)
The substrate processing method according to (5) above, wherein the Low-k film includes at least one selected from the group consisting of a SiOC film, a SiCN film, and a SiOCH film.
(7)
The substrate processing method according to any one of (1) to (6) above, wherein the mask contains at least one of carbon and metal.
(8)
The substrate processing method according to (7) above, wherein the carbon-containing mask includes at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.
(9)
The substrate processing method according to any one of (1) to (8) above, wherein the etching step is an etching step for forming a wiring layer of a logic circuit.
(10)
The substrate processing method according to any one of (1) to (9) above, wherein the plasma is a capacitively coupled plasma.

1 Plasma processing apparatus 2 Control section 2a Computer 2a1 Processing section 2a2 Storage section 2a3 Communication interface 10 Plasma processing chamber 10a Side wall 10e Gas exhaust port 10s Plasma processing space 11 Substrate support section 13 Shower head 13a Gas supply port 13b Gas diffusion chamber 13c Gas introduction Port 20 Gas supply section 21 Gas source 22 Flow rate controller 30 Power source 31 RF power source 31a, 31b RF generation section 32 DC power source 32a, 32b DC generation section 40 Exhaust system 111 Main body section 111a Central region 111b Annular region 112 Ring assembly 200 To be treated Layer 202 Silicon oxide film 204 Silicon nitride film 210, 212 Base layer 220 Mask 1110 Base 1110a Channel 1111 Electrostatic chuck 1111a Ceramic member 1111b Electrostatic electrode W Substrate

Claims (10)

A step of carrying into the chamber a substrate including a silicon-containing film and a mask stacked on the silicon-containing film;
generating plasma from a processing gas containing COF ₂ gas and hydrogen-containing gas, and etching the silicon-containing film;
including;
The flow rate of the hydrogen-containing gas relative to the total flow rate of the processing gas is 13% by volume or more and less than 50% by volume in terms of hydrogen gas.
Substrate processing method. The substrate processing method according to claim 1, wherein the hydrogen-containing gas includes at least one selected from the group consisting of hydrogen gas, hydrogen fluoride gas, and hydrofluoroolefin gas. The hydrofluoroolefin gases include C ₂ H ₂ F ₂ (1,1-difluoroethylene) gas, C ₃ H ₂ F ₄ (1,3,3,3-tetrafluoropropene) gas, and C ₄ H ₂ Containing at least one selected from the group consisting of F ₆ (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas,
The substrate processing method according to claim 2. The substrate processing method according to claim 1, wherein the processing gas further includes an inert gas, and the inert gas includes at least one of a rare gas and a nitrogen gas. The substrate processing method according to claim 1, wherein the silicon-containing film includes a silicon oxide film or a low-k film. 6. The substrate processing method according to claim 5, wherein the Low-k film includes at least one selected from the group consisting of a SiOC film, a SiCN film, and a SiOCH film. The substrate processing method according to claim 1, wherein the mask contains at least one of carbon and metal. 8. The substrate processing method according to claim 7, wherein the carbon-containing mask includes at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. The substrate processing method according to claim 1, wherein the etching step is an etching step for forming a wiring layer of a logic circuit. The substrate processing method according to claim 1, wherein the plasma is a capacitively coupled plasma.

Images