Etching method and etching device

Abstract

In an etching method according to the present disclosure, etching is carried out by exposing a carbon-containing silicon oxide film formed on a substrate to a plasma generated from an etching gas which includes a fluorine-containing gas, an oxygen-containing gas and hydrogen gas.

Description

Etching method and etching apparatus

[0001] The present disclosure relates to an etching method and an etching apparatus.

[0002] In manufacturing a semiconductor device, a carbon-containing silicon oxide film formed on the surface of a semiconductor wafer (hereinafter referred to as a wafer) serving as a substrate may be etched. ３ and CxFy, etching a carbon-containing silicon oxide film that is said to have less than about 30 atomic % carbon and less than about 50 atomic % hydrogen is described.

[0003] Special Publication No. 2004-512673

[0004] The present disclosure provides a technique that can satisfactorily etch a carbon-containing silicon oxide film.

[0005] In the etching method of the present disclosure, a carbon-containing silicon oxide film formed on a substrate is etched by exposing it to plasma generated from an etching gas containing a fluorine-containing gas, an oxygen-containing gas, and a hydrogen gas.

[0006] The present disclosure can successfully etch carbon-containing silicon oxide films.

[0007] Fig. 1 is a longitudinal sectional side view of a wafer undergoing an etching process according to an embodiment of the present disclosure; Fig. 2 is a longitudinal sectional side view of the wafer during etching; Fig. 3 is a longitudinal sectional side view of the wafer after etching; Fig. 4 is a longitudinal sectional side view of an etching apparatus that performs the etching process; Fig. 5 is a longitudinal sectional side view of a heat shield plate in the etching apparatus; Fig. 6 is a longitudinal sectional side view of another wafer before etching; and Fig. 7 is a graph showing results of an evaluation test.

[0008] An embodiment of an etching method according to the present disclosure will be described. The plasma etching method described in this embodiment is used as one step in the manufacturing process of a CFET (Complimentary Field Effect Transistor). This CFET has a structure in which an NMOS transistor and a PMOS transistor are stacked on a substrate in the thickness direction of the substrate. More specifically, the gates constituting each of these transistors overlap each other in the thickness direction of the substrate.

[0009] Then, semiconductor films called nanowires or nanosheets, which are made of Si (silicon) or SiGe (silicon germanium), extend through these gates in a direction perpendicular to the thickness direction of the substrate, and each semiconductor film is formed in multiple stages in the thickness direction of the substrate. By penetrating the gate in this way, each semiconductor film is surrounded by the gate, and the CFET has a so-called GAA (gate all around) structure. Note that this is an example of the process during the manufacture of a CFET, and it should be noted that the application of this technology is not limited to the manufacture of CFETs.

[0010] A wafer W, which is a substrate to be etched, will be described with reference to FIG. 1. FIG. 1 is a vertical cross-sectional side view of the surface layer of the wafer W. In the figure, two mutually perpendicular directions in the surface direction of the wafer W are indicated as the X direction and the Y direction, and a direction in the thickness direction of the wafer W, which is perpendicular to both the X direction and the Y direction, is indicated as the Z direction. FIG. 1 shows the wafer W as viewed in the X direction. In the following description of the film structure of the surface layer of the wafer W, the wafer W will be described as being placed on a horizontal surface. Therefore, the Z direction is the up-down direction.

[0011] On the wafer W, SiGe (silicon germanium) films 11 are formed so as to extend in the X direction. A large number of SiGe films 11 are provided at intervals in the Z direction, and each extends in the X direction. When viewed in the X direction, each SiGe film 11 except for the bottommost SiGe film 11 is surrounded by a SiOx (silicon oxide) film 12, as shown in the figure. Like the other SiGe films 11, the bottommost SiGe film 11 is also covered with a SiOx film 12. However, since this bottommost SiGe film 11 is formed so as to protrude upward from the surface of the wafer W, no SiOx film 12 is formed below this SiGe film 11. The SiGe films 11 of some of the stages of the SiGe films 11 formed in multiple stages as described above form the nanowires or nanosheets described above.

[0012] For ease of explanation, the plurality of SiGe films 11 covered with the SiOx film 12 and aligned in the Z direction will be collectively referred to as a semiconductor film array 13. Although not shown, a plurality of these semiconductor film arrays 13 are aligned in the Y direction on the wafer W. A SiOC film 14, which is a carbon-containing silicon oxide film, is formed to cover each semiconductor film array 13. More specifically, as viewed in the X direction, the SiOC film 14 is formed so as to extend from the left side of the semiconductor film array 13 across the upper side to the right side. The SiOC film 14 penetrates into the gaps between adjacent SiGe films 11 from the left and right of the semiconductor film array 13 (more specifically, the gaps formed by the SiOx film 12 surrounding the SiGe film 11 as shown in the figure) and fills these gaps.

[0013] The SiOC film 14 contains, for example, 20 atomic % or more and 40 atomic % or less of carbon. This atomic % can be measured by secondary ion mass spectrometry (SIMS) or X-ray photoelectron spectroscopy (XPS). The plasma etching of this embodiment removes portions of the SiOC film 14 located on the left, right, and upper sides of the semiconductor film array 13 as viewed in the X direction. Therefore, etching is performed so that portions of the SiOC film 14 interposed between the SiGe films 11 remain after processing.

[0014] When etching the SiOC film formed on the wafer W, HF (hydrogen fluoride) gas and NH ３ A technique is sometimes used in which an etching gas containing (ammonia) gas is turned into plasma and the SiOC film is exposed to the plasma. However, when etching a SiOC film having a relatively high carbon content, such as the SiOC film 14 of this embodiment, the etching amount per unit time is relatively small. Furthermore, such plasma etching has a relatively small etching selectivity to Si-containing films other than the SiOC film. In other words, the Si-containing film is etched to a relatively large extent.

[0015] In this embodiment, fluorine-containing gas NF ３ (nitrogen trifluoride) gas, O ２ (Oxygen) gas and H ２ A mixed gas consisting of (hydrogen) gas is supplied as an etching gas together with an inert gas for plasma generation into a processing vessel containing a wafer W. A vacuum atmosphere at a predetermined pressure is created inside the processing vessel. The wafer W is then exposed to the plasmatized etching gas, thereby etching the SiOC film 14.

[0016] 2, during this etching, some portions of the SiOx film 12 remain covered with the SiOC film 14, while other portions become exposed. In other words, both the SiOx film 12 and the SiOC film 14 are exposed on the surface of the wafer W. The arrows in the figure indicate plasma. Even when the SiOx film 12 is exposed on the surface of the wafer W, the plasma has high etching selectivity for the SiOC film 14, so the SiOC film 14 is selectively etched and etching of the SiOx film 12 is suppressed. Then, as shown in FIG. 3, once the portions of the SiOC film 14 covering the left, right, and upper sides of the semiconductor film array 13 are removed, plasma generation is stopped, and the etching process is completed.

[0017] As described above, the SiOC film 14 is etched with high selectivity relative to the SiOx film 12. Furthermore, as will be shown in the evaluation test described later, the etching rate (etching amount per unit time) of the SiOC film 14 is relatively high, and the etching process of this SiOC film 14 can be completed in a relatively short time. Note that, in FIG. 2 showing the state during etching, the upper portion of the SiOC film 14 is shown to be removed before the lower portion, but it is not limited to the upper portion being removed first as shown in this figure.

[0018] Next, an etching apparatus 2, which is one embodiment of an apparatus for performing the above-mentioned plasma etching process, will be described with reference to the vertical side view of Figure 4. The etching apparatus 2 includes a processing vessel 21 that stores a wafer W. The processing vessel 21 includes a vessel body 22 and a lid 23. The vessel body 22 forms the bottom wall and the lower sidewalls of the processing vessel 21, and the lid 23 forms the top wall and the upper sidewalls of the processing vessel 21. A horizontal partition plate 31 is provided within the processing vessel 21, dividing the interior of the processing vessel 21 into a processing space S surrounded by the vessel body 22 and a plasma generation space P surrounded by the lid 23. A heat shield plate 33 is also horizontally disposed below the partition plate 31 so as to divide the interior of the processing vessel 21 into upper and lower sections, similar to the partition plate 31.

[0019] An exhaust mechanism 24 equipped with a vacuum pump is connected to the bottom of the vessel body 22, and exhausts the interior of the processing vessel 21 to create a vacuum atmosphere at a desired pressure. A stage 25 is provided in the processing space S, and a wafer W is processed while horizontally placed on the upper surface of the stage 25. The upper surface of the stage 25 faces a heat shield 33. Two stages 25 are provided so that two wafers W can be processed simultaneously. However, because the two stages 25 are aligned in the front-to-back direction in FIG. 4 , only one stage 25 is shown in FIG. 4 . A temperature adjustment mechanism 26 is embedded in the stage 25 to adjust the temperature of the wafer W placed thereon. The temperature adjustment mechanism 26 is composed of, for example, a flow path through which a temperature-adjusted fluid by a chiller flows, a heater, and the like. In the figure, reference numeral 27 denotes a transfer port for the wafer W. This port opens in the sidewall of the vessel body 22 so that a transfer mechanism (not shown) can transfer the wafer W to the stage 25, and is opened and closed by a gate valve 28. In the drawing, 25A is an elevation mechanism that raises and lowers the stage 25 for this transfer.

[0020] A first gas supply unit 41 and a second gas supply unit 42 are provided outside the processing chamber 21. The first gas supply unit 41 supplies NF ３ Gas, O ２ Gas, H ２ The processing chamber 21 is provided with storage sections for storing the gases and the rare gas so that they can be supplied to the plasma generation space P, and a flow rate adjustment mechanism for adjusting the flow rate of the gas supplied from the storage sections to the plasma generation space P. The flow rate adjustment mechanism is configured, for example, with a valve or a mass flow controller. The rare gas, which is an inert gas, is specifically, for example, Ar (argon) gas, and plays a role in forming plasma and adjusting the pressure inside the processing chamber 21.

[0021] The second gas supply unit 42 supplies an inert gas, for example, N ２ In order to supply nitrogen gas to the processing space S through a heat shield plate 33 (to be described later), the gas storage unit and the flow rate adjusting mechanism are provided in the same manner as the first gas supply unit 41. ２ The gas is used as a pressure adjusting gas in the processing chamber 21 and as a dilution gas for the etching gas.

[0022] The partition plate 31 and the heat shield plate 33 will be described with reference to the vertical side view of Figure 5. Two partition plates 31 are arranged vertically with a gap between them, and each of the two partition plates 31 has a plurality of through holes 32. The through holes 32 of the upper partition plate 31 and the through holes 32 of the lower partition plate 31 are located at different positions in a plan view. By misaligning the positions of the through holes 32 in this way, the two partition plates 31 function as so-called ion traps that suppress the supply of ions in plasma generated in the plasma generation space P to the processing space S. Therefore, radicals, which are active species of plasma, are selectively supplied to the processing space S, thereby performing etching.

[0023] The heat shield 33 serves to prevent heat accumulated in the partition plate 31 due to repeated plasma generation in the plasma generation space P from affecting the distribution of radicals in the processing space S. The peripheral edge of the heat shield 33 forms a flange embedded in the side wall of the vessel body 22, and the heat shield 33 is cooled by a cooling mechanism 34 embedded in this flange. The cooling mechanism 34 is composed of, for example, a flow path through which a fluid whose temperature is adjusted by a chiller flows, or a Peltier element.

[0024] A plurality of through holes 36 are formed in the heat shield 33 so that radicals can be introduced from the plasma generation space P to the processing space S. In plan view, each through hole 36 overlaps with a through hole 32 in the lower partition plate 31. A number of gas outlets 37 are also formed on the lower surface of the heat shield 33. Gas supplied from the second gas supply unit 42 is supplied in a shower-like manner from the gas outlets 37 through a flow path formed inside the heat shield 33. Therefore, the heat shield 33 is configured as a shower head. The through holes 36 in the heat shield 33 and the through holes 32 in the partition plate 31 are omitted from FIG. 4 to avoid complication of the drawing.

[0025] Returning to Fig. 4, the lid 23 of the processing vessel 21 is made of, for example, quartz and serves as a dielectric window. A ring-shaped high-frequency antenna 43 is formed on the lid 23, and the high-frequency antenna 43 is connected to a high-frequency power supply 45 via a matching box 44. When high-frequency power of a predetermined frequency (for example, 13.56 MHz or higher) is output from the high-frequency power supply 45, inductively coupled plasma is generated from each gas supplied to the plasma generation space P. The high-frequency antenna 43, the matching box 44, and the high-frequency power supply 45 constitute a plasma generation mechanism.

[0026] The etching apparatus 2 includes a control unit 20, which is a computer, and includes a program, a memory, and a CPU. The program contains instructions (steps) for processing the wafer W and transporting the wafer W as described above. The program is stored on a storage medium, such as a compact disc, a hard disk, a magneto-optical disc, or a DVD, and is installed in the control unit 20. The control unit 20 outputs control signals to each component of the etching apparatus 2 based on the program, thereby controlling the operation of each component. The operations controlled in this manner include, for example, adjusting the temperature of the stage 25 (i.e., the processing temperature of the wafer W), the flow rates of the gases supplied from the first gas supply unit 41 and the second gas supply unit 42 to the processing chamber 21, the amount of exhaust by the exhaust mechanism 24 (i.e., adjusting the pressure inside the processing chamber 21), and switching on and off the high-frequency power supply 45 to generate and stop plasma generation.

[0027] The processing procedure for the wafer W using the etching apparatus 2 described above will now be described. The wafer W shown in FIG. 1 is placed on the stage 25. Then, with the pressure inside the processing chamber 21 set to, for example, 1.33 Pa to 133 Pa and the temperature of the wafer W set to, for example, 0°C to 120°C, each gas is supplied into the processing chamber 21 from the first gas supply unit 41 and the second gas supply unit 42 at a predetermined flow rate. An example of the flow rate ratio of each gas will be described in the evaluation test described later. Then, power of, for example, 200 W to 800 W is supplied from the high-frequency power source 45 to the high-frequency antenna 43, and the gases supplied to the plasma generation space P are converted into plasma.

[0028] Radicals constituting the plasma are supplied from the plasma generation space P to the processing space S, and the etching of the SiOC film 14 described with reference to FIGS. 1 to 3 progresses. Even if the SiOx film 12 is exposed during this etching, the etching of the SiOx film 12 is suppressed. Furthermore, the etching apparatus 2 suppresses the supply of relatively high-energy ions, among the activated species constituting the plasma, to the wafer W. Therefore, etching of the SiOC film 14 progresses while more reliably suppressing etching of the SiOx film 12. Then, as shown in FIG. 3, once the desired portion of the SiOC film 14 is etched, the power supply from the high-frequency power supply 45 and the supply of each gas into the processing chamber 21 are stopped, and the process is completed.

[0029] As will be shown in evaluation tests described later, the plasma etching of the present technology makes it possible to etch the SiOC film with high selectivity relative to the Si-containing film, even when a Si-containing film other than SiGe, such as Si or SiOx, and a SiOC film are present on the surface of the wafer W. The film structure of the wafer W shown in Fig. 6 is the same as that shown in Fig. 1 and is a film structure for manufacturing a CFET, but differs from that shown in Fig. 1 in that the SiOx film 12 is not formed on the surface of each SiGe film 11 constituting the semiconductor film array 13, and a SiOC film 14 is in contact with the SiGe film 11.

[0030] Since the plasma etching of the present technology has the above-mentioned selectivity, even if the SiGe film 11 is exposed during etching of the SiOC film 14 formed as shown in Fig. 6, it is possible to etch the SiOC film 14 around the semiconductor film array 13 while suppressing etching of the SiGe film 11. Fig. 7 shows the state at the end of this etching.

[0031] 1 and 6 show examples in which the semiconductor film array 13 is formed of the SiGe film 11, but it may be formed of a Si film instead of the SiGe film 11. Therefore, in Fig. 6, the Si film is exposed to the surface during etching of the SiOC film 14, but even in this case, the etching selectivity described above allows the SiOC film 14 to be etched while suppressing etching of the Si film.

[0032] In the above description of the CFET manufacturing process, an example has been given in which the SiOC film 14 covering the semiconductor film array 13 is plasma etched. That is, an example has been given in which the SiOC film 14 is etched so as to have an uneven surface corresponding to the shape of a pattern formed on the surface of the wafer W. However, as described above, this technology is not limited to application to the CFET manufacturing process, and the SiOC film 14 to be etched may have any shape. Therefore, for example, the SiOC film 14 formed as a flat film may be etched using the plasma described above.

[0033] In the etching examples described above, any one of the Si-containing films, the Si film, the SiGe film 11, and the SiOx film 12, is exposed to the surface during etching, so that the SiOC film 14 is selectively etched from among the Si-containing film and the SiOC film 14. The etching is not limited to the case where both the SiOC film 14 and the Si-containing film are exposed to the surface during etching. Alternatively, these films may be exposed on the surface of the wafer W before the start of etching, and the SiOC film 14 may be selectively etched relative to the Si-containing film from the start of etching. Therefore, for example, a wafer W formed so that both the SiOC film 14 and the Si-containing film are aligned in the surface direction of the wafer W and exposed on the surface may be loaded into the etching apparatus 2, and the SiOC film 14 may be selectively etched.

[0034] The above-mentioned Si-containing film is a film containing Si and different in type from the carbon-containing silicon oxide film to be etched, for example, a film not containing carbon. More specifically, the Si-containing film may be, for example, the Si film, SiGe film, SiOx film, or a SiN (silicon nitride) film. It has been shown in the evaluation test described below that the above-mentioned plasma etching also increases the etching selectivity of the carbon-containing silicon oxide film relative to the SiN film. The reason why the etching of each Si-containing film is suppressed in this way is that the O content of the etching gas is low. ２ Gas and H ２It is believed that activated species of the plasma generated from the gas adhere to the surface of the Si-containing film and function as a protective film against the plasma.

[0035] Furthermore, when etching the SiOC film 14 with the above-described plasma, it is not limited to forming a state in which both the SiOC film 14 and the Si-containing film are exposed on the surface. In other words, etching may be performed such that only the SiOC film 14 is exposed on the surface of the substrate from the start to the end of the process. Even in this case, the present technology can achieve the effect of etching the SiOC film 14 at a relatively high etching rate.

[0036] Now, a supplementary explanation about the Si-containing film will be provided. Here, "a film containing Si" does not mean that Si is inevitably contained as an impurity, but that Si is contained as a constituent component. In this specification, when a film other than the Si-containing film or an etching gas contains a specific component, this means that the film or etching gas contains the component as a constituent component, similar to the Si in the Si-containing film, but does not mean that the film or etching gas contains the component as an impurity. Furthermore, while the Si-containing film has been described as being a carbon-free film, this "carbon-free" means that the film does not contain carbon as a constituent component, and does not mean that the film does not contain carbon, which is inevitably mixed in as an impurity.

[0037] The carbon-containing silicon oxide film to be etched is not limited to the SiOC film 14. Specifically, the etching target may be, for example, a film configured as a SiCOH film by containing hydrogen in addition to Si, O, and C, or a film configured as a SiOCN film by containing nitrogen. The atomic percentage of carbon contained in these SiCOH films and SiOCN films is the same as the range of atomic percentage of carbon contained in the SiOC film 14 described above.

[0038] The fluorine-containing gas constituting the etching gas is NF ３ Not limited to gas, F ２Other gases containing fluorine, such as (fluorine) gas, may also be used. Also, although an example in which oxygen is used as the oxygen-containing gas constituting the etching gas has been shown, O ３ (ozone) gas, CO (carbon monoxide) gas, CO ２ Even if a gas such as carbon dioxide is used, oxygen radicals can be supplied to the wafer W, and it is believed that the same effect as when oxygen gas is used can be obtained.

[0039] Although the etching apparatus 2 described above is configured to generate inductively coupled plasma, any method for generating plasma may be used. For example, an apparatus may be used in which the showerhead and stage provided in the processing chamber are configured as parallel plate electrodes facing each other, and a capacitively coupled plasma is generated by gas supplied from the showerhead toward the stage, thereby etching the wafer W on the stage. Alternatively, so-called remote plasma processing may be performed, in which plasma generated at a location remote from the processing chamber is supplied into the processing chamber. However, in an apparatus configuration in which inductively coupled plasma is generated in the processing chamber, it is advantageous to provide a partition plate 31 that functions as an ion trap, as described with reference to FIGS. 4 and 5, in order to suppress etching of the Si-containing film due to the action of ions.

[0040] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, modifications, and combinations may be made in the above-described embodiments without departing from the scope and spirit of the appended claims.

[0041] [Evaluation Test] An evaluation test conducted in connection with the technology of the present disclosure will be described. A wafer W with five chips mounted on its surface was prepared. A film was formed on the top surface of each chip, and the type of film formed differed between the chips. Specifically, the formed films were SiOC film, SiN film, SiOx film, polysilicon film, and SiGe film, and one of these films was formed on each chip. In this evaluation test, the SiOC film contained carbon at a concentration of 30 atomic % or more and 40 atomic % or less.

[0042] As an evaluation test, the wafer W was loaded into the etching apparatus 2 described in the embodiment and subjected to a plasma etching process for a predetermined time. After the etching process, the etching amount of the film formed on each chip was measured. Furthermore, for films other than the SiOC film, the etching selectivity was calculated based on the etching amount of the SiOC film. This etching selectivity is a value calculated by dividing the etching amount of the SiOC film by the etching amount of the film for which the etching selectivity is to be calculated. Therefore, the larger the etching selectivity, the more the etching amount of that film is suppressed, and the higher the etching selectivity to the SiOC film.

[0043] In the etching process in this evaluation test, the pressure inside the processing vessel 21 and the power supplied from the high frequency power source 45 were set to values ​​within the ranges described in the embodiment. ３ : H ２ Gas: O ２ Gas: N ２ The ratio of gas to Ar gas was 1:1:1:14:1.

[0044] FIG. 8 is a graph showing the results of this evaluation test. The vertical axis of the graph represents the etching amount, and the vertical axis is marked with a scale in predetermined increments A. The etching selectivity ratios were 26.8, 97.7, 157.9, and 42.3 for the SiN film, SiOx film, polysilicon film, and SiGe film, respectively. Thus, the etching selectivity ratios were relatively high for all of the SiN film, SiOx film, polysilicon film, and SiGe film. Therefore, as described in the embodiment, it was confirmed that, when etching a SiOC film using this technology, the etching amount of Si-containing films other than the SiOC film is suppressed, and a high etching rate for the SiOC film is obtained. In particular, the etching selectivity ratios for the SiOx film, polysilicon film, and SiGe film are high, demonstrating that this technology is effective when etching a SiOC film relative to these films. Therefore, as described in the embodiment, it was demonstrated that this technology is effective when applied to the CFET manufacturing process, in which these films are exposed during the etching of the SiOC film.

[0045] Since such a high etching selectivity can be obtained for each Si-containing film, it is expected that a practically sufficient etching selectivity can be obtained even if the carbon content of the SiOC film is less than 30 atomic %. Specifically, as described in the embodiment, it is believed that a sufficient etching selectivity can be obtained for an SiOC film containing 20 atomic % or more of carbon.

[0046] In addition, NF ３ Gas, O ２ Gas, H ２ The gas flow rate ratio in this evaluation test was 1:1:1, but since a very high etching selectivity was obtained for each Si-containing film as described above, it is believed that even if the flow rate ratio is slightly changed, sufficient effects can be obtained in practice. ３ If the gas flow rate is 1, then O ２ Gas flow rate is 0.2 to 10, H ２ It is expected that etching can be performed with a sufficient selectivity even if the gases are supplied to the wafer W at a flow rate of 0.2 to 10. ３ When the gas flow rate is 1, ２ Gas flow rate and H ２ By setting the flow rates of the gases to 0.5 to 1.5 and setting the ratio closer to the conditions set in the test, etching with a good selectivity can be performed more reliably. ２ No gas included, NF ３ Gas and O ２ When only the gas was supplied, high etching selectivity for the SiOC film as shown in this evaluation test could not be obtained. Therefore, in order to increase the etching selectivity for the SiOC film, it was necessary to add H ２ It is effective to include a gas.

[0047] W wafer 14 SiOC film

Claims

1. An etching method in which a carbon-containing silicon oxide film formed on a substrate is etched by exposing it to plasma generated from an etching gas containing a fluorine-containing gas, an oxygen-containing gas, and a hydrogen gas.

2. The etching method of claim 1, wherein said oxygen-containing gas is oxygen.

3. The etching method of claim 2, wherein said fluorine-containing gas is nitrogen trifluoride.

4. The etching method according to claim 3, wherein the carbon-containing silicon oxide film is a SiOC film.

5. The etching method according to claim 1, wherein the carbon content in said carbon-containing silicon oxide film is 20 atomic % or more and 40 atomic % or less.

6. The etching method according to claim 1, further comprising the steps of: providing the substrate with the carbon-containing silicon oxide film and a silicon-containing film; exposing the carbon-containing silicon oxide film and the silicon-containing film to the plasma; and selectively etching the carbon-containing silicon oxide film out of the carbon-containing silicon oxide film and the silicon-containing film.

7. The etching method according to claim 6, wherein the silicon-containing film is a silicon film, a silicon oxide film or a silicon germanium film.

8. An etching apparatus comprising: a processing vessel for storing a substrate on which a carbon-containing silicon oxide film is formed; a gas supply unit for supplying an etching gas containing a fluorine-containing gas, an oxygen-containing gas, and a hydrogen gas into the processing vessel; and a plasma generating mechanism for generating plasma of the etching gas to etch the carbon-containing silicon oxide film by exposing the carbon-containing silicon oxide film to the plasma.

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