Film formation method and film formation apparatus

Abstract

To provide a deposition method and a deposition device which can easily deposit an SiOC-based film having the high controllability of film characteristics such as film composition, wet etching resistance and electric characteristics.SOLUTION: A deposition method comprises the steps of: depositing an SiC-based film on a substrate by using a carbon precursor and a silicon precursor; forming an SiOC-based film by performing oxidation treatment on the SiC-based film on the substrate; and performing treatment using plasma of gas containing H2 gas to the SiOC-based film on the substrate. The step of depositing the SiC-based film is performed until the SiC-based film has a given film thickness. The method executes an operation of performing the step of depositing the SiC-based film, the step of forming the SiOC-based film by the oxidation treatment one or plural times until the SiOC-based film has the given film thickness. The method executes the operation of forming the SiOC-based film until the SiOC-based film has the given film thickness and the step of performing the treatment using plasma one or plural times.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a film formation method and a film formation apparatus. [Background technology]

[0002] Silicon-containing films are widely used in semiconductor devices, and Patent Document 1 describes a method for forming a SiC-containing film on a substrate as a silicon-containing film suitable for a hard mask, using a carbon precursor gas containing an organic compound with an unsaturated carbon bond and a silicon precursor gas containing a silicon compound.

[0003] On the other hand, SiOC film is known as an insulating silicon-containing film with a low relative dielectric constant (k value) and high etching resistance (chemical treatment resistance).Patent Document 2 describes a method for forming an SiOC film with high controllability of C concentration by repeatedly performing a step of forming a first film containing Si, O, and C using a silicon compound having an Si-O bond as a source gas, and a step of forming a second film containing Si and C using a carbon-containing precursor and a silicon-containing precursor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-158133 [Patent Document 2] Japanese Patent Application Publication No. 2022-67559 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a film formation method and a film formation apparatus that can easily form an SiOC-based film with high controllability over film composition and film properties such as wet etching resistance and electrical properties. [Means for solving the problem]

[0006] A film formation method according to one aspect of the present disclosure is a film formation method for forming a SiOC-based film, the method comprising the steps of: preparing a substrate; forming a SiC-based film on the substrate using a carbon precursor made of a carbon-containing gas and a silicon precursor made of a silicon-containing gas; oxidizing the SiC-based film on the substrate to form a SiOC-based film; and treating the SiOC-based film on the substrate with plasma of a gas containing H gas, wherein the step of forming the SiC-based film is performed until the SiC-based film reaches a predetermined thickness; performing the steps of forming the SiC-based film and forming the SiOC-based film by the oxidation treatment one or more times until the SiOC-based film reaches a predetermined thickness; and performing the step of forming the SiC-based film until the SiOC-based film reaches the predetermined thickness and the step of treating with plasma one or more times. The step of forming the SiC-based film uses an organic compound gas as the carbon precursor, and the organic compound gas has a triple bond between carbon atoms. . [Effects of the Invention]

[0007] According to the present disclosure, there are provided a film formation method and a film formation apparatus that can easily form an SiOC-based film with high controllability over film composition and film properties such as wet etching resistance and electrical properties. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an example of a flowchart illustrating a film forming method according to an embodiment. [Figure 2] FIG. 10 is a diagram showing a flow when the SiC-based film of ST2 is formed by ALD. [Figure 3] 1 is a cross-sectional view showing an example of a film forming apparatus used to carry out a film forming method according to an embodiment. [Figure 4] 10 is a chart showing gas supply, pressure, and APC opening degree when performing a SiC film deposition process in ST2, an oxidation process in ST3, and a plasma process in ST4. [Figure 5] FIG. 10 is a diagram showing the relationship between the number of cycles x during SiC-based film formation corresponding to the frequency of oxidation treatment and the film composition. [Figure 6] FIG. 6 is a diagram showing the relationship between the film thickness and film composition of a SiC-based film after one oxidation treatment, with x in FIG. 5 replaced with film thickness. [Figure 7] FIG. 10 is a diagram showing the relationship between the number of cycles x until an oxidation treatment is performed during SiC-based film formation and DHF resistance, corresponding to the frequency of the oxidation treatment. [Figure 8] FIG. 10 is a diagram showing the relationship between the number of cycles x during SiC-based film formation, which corresponds to the frequency of oxidation treatment, and the k value and leakage value of the film. [Figure 9] FIG. 10 is a diagram showing the relationship between the number of cycles y corresponding to the frequency of H plasma treatment and the film composition when the number of cycles x until the oxidation treatment is performed during the deposition of a SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 10] FIG. 10 is a graph showing the relationship between the number of cycles y corresponding to the frequency of H plasma treatment and the DHF resistance of the film when the number of cycles x until the oxidation treatment is performed during the deposition of a SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 11] FIG. 10 is a diagram showing the relationship between the number of cycles y corresponding to the frequency of H plasma treatment and the k value and leakage value of the film when the number of cycles x until the oxidation treatment is performed during the deposition of a SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 12] FIG. 1 is a graph showing the relationship between the O concentration and the WER for 50% DHF in SiOC films formed under various conditions. [Figure 13] FIG. 13 is an enlarged view of a part of FIG. 12. [Figure 14] FIG. 1 is a graph showing the relationship between the O concentration and the k value in SiOC films formed under various conditions. [Figure 15] FIG. 1 is a diagram showing the relationship between the O concentration and the leakage value in SiOC-based films formed under various conditions. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments will be specifically described with reference to the accompanying drawings.

[0010] <Film formation method> 1 is an example of a flowchart showing a film formation method according to one embodiment. The film formation method according to one embodiment includes a step (ST1) of preparing a substrate, a step (ST2) of forming a SiC-based film on the substrate using a carbon precursor and a silicon precursor, a step (ST3) of oxidizing the SiC-based film on the substrate to form a SiOC-based film, and a step (ST4) of treating the SiOC-based film on the substrate with plasma of a gas containing H2 gas.

[0011] As shown in Figure 1, the deposition of a SiC-based film in ST2 is performed until it reaches a predetermined thickness, and this ST2 and the formation of a SiOC-based film by oxidation treatment in ST3 are performed one or more times until the SiOC-based film reaches the predetermined thickness. The SiOC-based film thus formed is then subjected to H2 plasma treatment in ST4 to modify the SiOC-based film. The process of forming a SiOC-based film until it reaches the predetermined thickness (ST2 and ST3 are performed one or more times) and the process of performing H2 plasma treatment in ST4 are performed one or more times until the modified SiOC-based film reaches the predetermined thickness.

[0012] In ST1, the substrate is not particularly limited, but may be a semiconductor substrate (semiconductor wafer) such as silicon.

[0013] In ST2, a carbon precursor and a silicon precursor are used and reacted on the substrate to form a SiC-based film. The SiC-based film may contain impurities and additives in addition to SiC.

[0014] The carbon precursor is composed of a carbon-containing gas. An organic compound gas can be used as the carbon-containing gas. The organic compound gas used as the carbon-containing gas preferably has an unsaturated carbon bond, i.e., a double or triple bond between carbon atoms. Organic compounds with unsaturated carbon bonds are highly reactive, making it possible to form SiC-based films at lower temperatures. Examples of organic compounds with unsaturated bonds include those having a skeleton, which is the unsaturated carbon bond portion, and a side chain bonded to the skeleton. Examples of side chains include hydrogen atoms, halogens, alkyl groups with 5 or less carbon atoms, double or triple carbon bonds, and groups in which the carbon bond to the skeleton is Si, C, N, or O. The unsaturated carbon bond forming the skeleton may be a double bond or a triple bond, but a triple bond is more preferable. Specific examples of organic compound gases having a triple bond (acetylene-based gases) include bistrimethylsilylacetylene (BTMSA), trimethylsilylacetylene (TMSA), trimethylsilylmethylacetylene (TMSMA), and bischloromethylacetylene (BCMA).

[0015] The silicon precursor is made of a silicon-containing gas. Examples of the silicon-containing gas include a gaseous compound having a Si-containing skeleton and a side chain bonded to the skeleton. Examples of the skeleton include Si-Si, Si-C, Si-N, and Si-O. Examples of the side chain include a hydrogen atom, a halogen, an alkyl group having 5 or less carbon atoms, a carbon double or triple bond, and a group in which the site bonded to the Si in the skeleton is Si, C, N, or O. Examples of the silicon-containing gas that constitutes the silicon precursor include a silane-based compound gas. Specific examples include disilane, monosilane, trisilane, and dichlorosilane. Organosilane-based compound gases such as aminosilane may also be used.

[0016] The deposition of the SiC-based film in ST2 can be performed using ALD (Atomic Layer Deposition), which sequentially supplies a carbon precursor and a silicon precursor. Alternatively, CVD (Chemical Vapor Deposition), which simultaneously supplies a carbon precursor and a silicon precursor, can be used. These methods can be performed by thermal reactions. By using ALD, a SiC film can be deposited at low temperatures with good controllability through a thermal reaction that does not use plasma. In addition, by using an organic compound gas having an unsaturated carbon bond as the carbon precursor, the deposition temperature can be further reduced, making it possible to deposit the film at less than 800°C.

[0017] In particular, by using an organic compound gas (acetylene-based gas) having a triple bond such as BTMSA as a carbon precursor and disilane as a silicon precursor, it is possible to form a film at a low temperature of 500°C or less through the following mechanism, as also described in Patent Document 2.

[0018] Disilane thermally decomposes when heated to around 400°C, generating SiH2 radicals with unpaired electrons on the Si atom. These SiH2 radicals are polarized into σ+ and σ-. Of these, the positively polarized σ+ acts as an electrophile that attacks the unsaturated π bond of an organic compound gas with a triple bond, decomposing the organic compound gas with a triple bond. The C in the triple bond reacts with the Si in the SiH2 radical to form an Si-C bond. Because the π bond of a triple bond has a weaker bonding strength than the σ bond, when the SiH2 radical attacks the π bond, the thermal reaction proceeds sufficiently even at substrate temperatures below 500°C to generate an Si-C bond.

[0019] The above mechanism only applies when an acetylene-based gas is used as the carbon precursor and disilane is used as the silicon precursor. However, if an organic compound gas having an unsaturated carbon bond, particularly a triple bond, is used as the carbon precursor, it is believed that a similar mechanism can be used to lower the film formation temperature.

[0020] When depositing a SiC-based film in ST2 by ALD, as shown in Figure 2, a cycle of supplying a carbon precursor (ST2-1), removing residual gas (ST2-2), supplying a silicon precursor (ST2-3), and removing residual gas (ST2-4) is repeated multiple times. In ST2-1, a carbon precursor is supplied to the substrate, causing it to adsorb onto the substrate. In ST2-2, excess residual gas is removed. Then, in ST2-3, a silicon precursor is supplied to the substrate, causing the carbon precursor adsorbed on the substrate to react with the silicon precursor to form a SiC unit film. In ST2-4, excess residual gas is removed. By repeating these steps, ST2-1 to ST2-4, a SiC-based film of the desired thickness is obtained.

[0021] In the oxidation process in ST3, after a SiC-based film of a given thickness is formed on the substrate in ST2, an oxygen-containing gas is supplied to oxidize the SiC-based film to form a SiOC-based film. Semiconductor devices require insulating silicon-containing films with a low k value and high etching resistance (resistance to chemical treatment), and SiOC-based films are silicon-containing films that possess these properties. The SiC-based film is obtained with a given thickness by performing the deposition and oxidation process of the SiC-based film once or multiple times. The SiOC-based film may contain impurities and additives in addition to SiOC.

[0022] The oxygen-containing gas used in the oxidation treatment can be O2 gas, H2O gas, O3 gas, or H2O2 gas. The oxidation treatment can be performed by a thermal reaction. Alternatively, plasma of an oxygen-containing gas can be used. The temperature during the oxidation treatment is not particularly limited as long as the SiC-based film is oxidized, but the oxidation treatment can be performed at the same temperature as the temperature used in forming the SiC-based film in ST2.

[0023] The composition of the SiC-based film (O concentration in the film) can be controlled by adjusting the film thickness of the SiC-based film before the oxidation treatment in ST3 (the film thickness of the SiC-based film after one oxidation treatment and before the next oxidation treatment). The film thickness of the SiC-based film during the oxidation treatment in ST3 can also be understood as the frequency of the oxidation treatment; the thinner the SiC-based film, the higher the frequency of the oxidation treatment and the higher the oxygen concentration in the film. The film thickness of the SiC-based film during the oxidation treatment may be in the range of 0.9 to 3.2 Å (0.09 to 0.32 nm). By setting the film thickness of the SiC-based film during the oxidation treatment in this range, the O concentration in the film can be set to 26 to 42 at%. As described below, this improves wet etching resistance.

[0024] When the film is formed by ALD, the thickness of the SiC-based film corresponds to the number of ALD cycles. For example, when TMSA gas is used as the carbon-containing gas and disilane gas is used as the silicon-containing gas, the film formation temperature is about 450°C, and one ALD cycle corresponds to a film thickness of about 0.32 Å. Therefore, the above-mentioned range of film thicknesses of 0.9 to 3.2 Å corresponds to 3 to 10 cycles.

[0025] The composition of the SiOC-based film can also be controlled by changing the oxidation conditions such as the flow rate of the oxygen-containing gas and the oxidation time.

[0026] The treatment with plasma of a gas containing H2 gas in ST4 is a modification treatment of the SiOC-based film formed by the oxidation treatment in ST3. As described above, when forming a SiC-based film, a carbon-containing gas and a silicon-containing gas are used as carbon precursors and silicon precursors, respectively. However, since the carbon-containing gas is generally an organic compound gas and the silicon-containing gas is generally a silane-based gas, the SiOC-based film contains a large amount of H. Therefore, in ST4, the SiOC-based film formed by the oxidation treatment in ST3 is treated with plasma of a gas containing H2 gas (hereinafter simply referred to as "H2 plasma treatment") to perform a modification treatment that mainly removes H components from the film. The modification treatment densifies the SiOC-based film, changes the film composition, and also improves wet etching resistance (chemical treatment resistance).

[0027] The gas containing H2 gas may be H2 gas alone or may be H2 gas plus an inert gas such as Ar gas. The temperature during the H2 plasma treatment in ST4 is not particularly limited as long as the desired modification is achieved, but the temperature may be the same as the temperature during the deposition of the SiC-based film in ST2.

[0028] The modification effect can be controlled by adjusting the thickness of the SiOC-based film before H2 plasma treatment. The thickness of the SiOC-based film during the H2 plasma treatment in ST4 can also be understood as the frequency of H2 plasma treatment; the thinner the SiOC-based film, the higher the frequency of H2 plasma treatment. By controlling the frequency of H2 plasma treatment, the film composition can be controlled, and the resulting changes in wet etching resistance (chemical treatment resistance) and electrical properties (k value, leakage characteristics) can be controlled. For example, reducing the frequency of H2 plasma treatment tends to increase the O2 concentration of the film and decrease wet etching resistance (chemical treatment resistance).

[0029] The thickness of the SiOC-based film before H2 plasma treatment can be in the range of 0.4 to 18.7 Å, and can be optimized within this range depending on the desired characteristics. If the thickness of the SiOC-based film before H2 plasma treatment is thin (i.e., if the H2 plasma treatment is performed frequently), the k value tends to be high. On the other hand, if the thickness of the SiOC-based film before H2 plasma treatment is thick (i.e., if the H2 plasma treatment is performed infrequently), the modification effect by the H2 plasma treatment tends to be small.

[0030] The modification effect can also be controlled by adjusting the processing conditions of the H2 plasma treatment. For example, by extending the processing time of the H2 plasma treatment, the modification effect can be further enhanced, and even if the thickness of the SiOC-based film before the plasma treatment is the same, the wet etching resistance and leakage characteristics can be improved.

[0031] Although the deposition of the SiC film in ST2, the oxidation treatment in ST3, and the plasma treatment in ST4 may be performed in separate chambers, it is preferable to perform them in the same chamber. By performing these in the same chamber, ST2 to ST4 can be performed without the need for substrate transport, allowing for high throughput.

[0032] As described above, according to the present embodiment, the controllability of the film properties such as the film composition, wet etching resistance, and electrical properties of the SiOC-based film can be improved by a simple method of adjusting the frequency and conditions of the oxidation treatment and the frequency and conditions of the H plasma treatment.

[0033] Furthermore, by adjusting the thickness and oxidation conditions of the SiC-based film during oxidation treatment, and the thickness and time of the SiOC-based film during H2 plasma treatment, it is possible to form a SiOC-based film with the desired film composition and film properties. For example, the oxygen concentration of the SiOC-based film can be controlled to 10 to 60 at%. Within this range, by setting the oxygen concentration to 10 to 45 at% it is possible to improve wet etching resistance. In particular, by setting the oxygen concentration to 26 to 42 at% it is possible to reduce the wet etching rate with dilute hydrofluoric acid (DHF) to 10 Å / min or less. Furthermore, by setting the oxygen concentration to 34 at% or more, it is possible to reduce the k value to 4.5 or less and the leakage characteristics (leak value) at 2 MV / cm to 10 × 10 -8 A / cm 2 Furthermore, by optimizing the frequency of the oxidation treatment and the frequency or time of the H2 plasma treatment, the k value can be reduced to 4 or less and the leakage value to 10 x 10 -9 A / cm 2 Furthermore, by setting the oxygen concentration to 34 to 45 at %, it is possible to improve the wet etching characteristics, k value, and leakage characteristics.

[0034] <Film forming equipment> Next, we will explain an example of a film formation apparatus used to form the above-mentioned SiOC-based film. Here, we show a single-wafer film formation apparatus that uses a semiconductor wafer (hereinafter simply referred to as "wafer") as the substrate, and that can form a SiC-based film on the wafer by ALD, as well as perform oxidation and plasma treatment. Also, trimethylsilylacetylene (TMSA) gas is used as the carbon precursor, disilane (DS) gas as the silicon precursor, O gas as the oxygen-containing gas, and Ar gas as the inert gas.

[0035] FIG. 3 is a cross-sectional view showing an example of a film forming apparatus used to form a SiOC-based film. As shown in FIG. 3, the film forming apparatus 100 includes a chamber 1, a susceptor 2, a shower head 3, an exhaust unit 4, a gas supply mechanism 5, a plasma generation mechanism 6, and a control unit .

[0036] The chamber 1 is made of a metal such as aluminum and has a generally cylindrical shape. A loading / unloading port 11 is formed in the side wall of the chamber 1 for loading and unloading the wafer W, and the loading / unloading port 11 can be opened and closed by a gate valve 12. An annular exhaust duct 13 with a rectangular cross section is provided above the main body of the chamber 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed in the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 to close the upper opening of the chamber 1. An insulating ring 16 is fitted around the outer periphery of the ceiling wall 14, and a seal ring 15 provides an airtight seal between the insulating ring 16 and the exhaust duct 13.

[0037] The susceptor 2 is used to horizontally support the wafer W within the chamber 1. The susceptor 2 is disk-shaped and sized to accommodate the wafer W, and is supported by a support member 23. The susceptor 2 is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as aluminum or a nickel-based alloy, and has a heater 21 embedded therein for heating the wafer W. The heater 21 generates heat when power is supplied from a heater power supply (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the wafer-mounting surface on the upper surface of the susceptor 2, thereby controlling the temperature of the wafer W at a predetermined level.

[0038] The susceptor 2 is provided with a cover member 22 made of ceramics such as alumina so as to cover the outer peripheral region of the wafer mounting surface and the side surfaces of the susceptor 2 .

[0039] A support member 23 that supports the susceptor 2 extends from the center of the bottom surface of the susceptor 2 to below the chamber 1, passing through a hole formed in the bottom wall of the chamber 1, and its lower end is connected to an elevation mechanism 24, which enables the susceptor 2 to be raised and lowered via the support member 23 between a processing position shown in Fig. 3 and a transfer position, shown by a dashed line below, where a wafer can be transferred. In addition, a flange member 25 is attached to the support member 23 below the chamber 1, and a bellows 26 is provided between the bottom surface of the chamber 1 and the flange member 25 to separate the atmosphere inside the chamber 1 from the outside air, and which expands and contracts as the susceptor 2 is raised and lowered.

[0040] Three wafer support pins 27 (only two shown) are provided near the bottom surface of the chamber 1, protruding upward from a lift plate 27a. The wafer support pins 27 can be raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the chamber 1, and are inserted into through holes 2a provided in the susceptor 2 at the transfer position, so that they can be protruded and retracted relative to the upper surface of the susceptor 2. By raising and lowering the wafer support pins 27 in this manner, the wafer W is transferred between a wafer transfer mechanism (not shown) and the susceptor 2.

[0041] The showerhead 3 is a metal member for supplying processing gas into the chamber 1 in a shower-like manner, and is disposed opposite the susceptor 2. The showerhead 3 has a main body 31 fixed to the ceiling wall 14 of the chamber 1 and a shower plate 32 connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32, and a gas inlet hole 36 is connected to this gas diffusion space 33, the gas inlet hole 36 penetrating the center of the main body 31 and the ceiling wall 14 of the chamber 1. A downwardly protruding annular protrusion 34 is formed on the periphery of the shower plate 32, and gas outlet holes 35 are formed on the flat surface on the inner side of the annular protrusion 34 of the shower plate 32.

[0042] When the susceptor 2 is in the processing position, a processing space 37 is formed between the shower plate 32 and the susceptor 2, and the annular protrusion 34 and the upper surface of the cover member 22 of the susceptor 2 are close to each other to form an annular gap 38.

[0043] The exhaust unit 4 is used to exhaust the inside of the chamber 1, and includes an exhaust pipe 41 connected to the exhaust port 13b of the exhaust duct 13, an automatic pressure control valve (APC) 42 connected to the exhaust pipe 41, and a vacuum pump 43. During processing, gas inside the chamber 1 reaches the exhaust duct 13 through the slit 13a, and is exhausted from the exhaust duct 13 through the exhaust pipe 41 by the exhaust mechanism 42 of the exhaust unit 4.

[0044] The gas supply mechanism 5 supplies gas to the showerhead 3 and includes a TMSA gas supply source 51, a DS gas supply source 52, a first Ar gas supply source 53, a second Ar gas supply source 54, an O gas supply source 55, and an H gas supply source 56. The TMSA gas supply source 51 supplies TMSA gas as a carbon-containing gas when forming a SiC film. The DS gas supply source 52 supplies DS gas as a silicon-containing gas when forming a SiC film. The first Ar gas supply source 53 and the second Ar gas supply source 54 supply Ar gas that functions as an additive gas, carrier gas, purge gas, etc. The O gas supply source 55 supplies O gas as an oxygen-containing gas used in oxidation processing. The H gas supply source 56 supplies H gas used in plasma processing.

[0045] The gas supply mechanism 5 further includes a TMSA gas supply pipe 61, a DS gas supply pipe 62, a first Ar gas supply pipe 63, a second Ar gas supply pipe 64, an O gas supply pipe 65, and an H gas supply pipe 66. The TMSA gas supply pipe 61 extends from the TMSA gas supply source 51, the DS gas supply pipe 62 extends from the DS gas supply source 52, the first Ar gas supply pipe 63 extends from the first Ar gas supply source 53, and the second Ar gas supply pipe 64 extends from the second Ar gas supply source 54. The O gas supply pipe 65 extends from the O gas supply source 55, and the H gas supply pipe 66 extends from the H gas supply source 56.

[0046] The TMSA gas supply pipe 61 and the DS gas supply pipe 62 join together at a joining pipe 66, which is connected to the gas inlet 36. The first Ar gas supply pipe 63 is connected to the TMSA gas supply pipe 61, and the second Ar gas supply pipe 64, the O gas supply pipe 65, and the H gas supply pipe 66 are connected to the DS gas supply pipe 62.

[0047] The TMSA gas supply pipe 61 is provided with, from upstream, a flow rate controller 71 such as a mass flow controller, a storage tank 77, and an on-off valve 81. The DS gas supply pipe 62 is provided with, from upstream, a flow rate controller 72, a storage tank 78, and an on-off valve 82. The first Ar gas supply pipe 63 is provided with, from upstream, a flow rate controller 73 and an on-off valve 83, and the second Ar gas supply pipe 64 is provided with, from upstream, a flow rate controller 74 and an on-off valve 84. The O gas supply pipe 65 is provided with, from upstream, a flow rate controller 75, a storage tank 79, and an on-off valve 85. The H gas supply pipe 66 is provided with, from upstream, a flow rate controller 76 and an on-off valve 86.

[0048] By switching on / off valves 81, 82, 83, 84, 85, and 86, it is possible to perform an ALD process, oxidation treatment, or plasma treatment, as described below. Storage tanks 77, 78, and 79 temporarily store the corresponding gases and pressurize them to a predetermined pressure. In this state, the on / off valves are opened to supply the gases into chamber 1.

[0049] The purge gas is not limited to Ar gas, but may be other inert gases such as N 2 gas or rare gases other than Ar.

[0050] The plasma generation mechanism 6 includes a power supply line 91 connected to the main body 31 of the showerhead 3, a matching box 92 and a high-frequency power supply 93 connected to the power supply line 91, and an electrode 94 embedded in the susceptor 2. When high-frequency power is supplied from the high-frequency power supply 91 to the showerhead 3, a high-frequency electric field is formed between the showerhead 3 and the electrode 94. This high-frequency electric field generates plasma of a gas containing H2 gas during plasma processing. The gas containing H2 gas may be H2 gas alone, or H2 gas with Ar gas added. The frequency of the high-frequency power supply 83 is preferably set to 450 kHz to 100 MHz, and is, for example, 40 MHz. The plasma generation mechanism 6 may also generate plasma of O2 gas, an oxygen-containing gas, during oxidation processing.

[0051] The control unit 7 includes a main control unit made up of a computer (CPU) that controls each component of the film formation apparatus, such as a valve, mass flow controller, power supply, heater, vacuum pump, etc., as well as an input device, an output device, a display device, and a storage device. The storage device stores parameters for various processes executed in the film formation apparatus 100. The storage device also includes a storage medium that stores programs for controlling the processes executed in the film formation apparatus 100, i.e., process recipes. The main control unit calls up a predetermined process recipe stored in the storage medium and causes the film formation apparatus 100 to perform a predetermined operation based on the process recipe.

[0052] In the film forming apparatus 100 configured as described above, first, the gate valve 12 is opened, and a transfer device (not shown) loads the substrate W into the chamber 1 via the load / unload port 11, and the substrate W is placed on the susceptor 2. The transfer device is retracted, and the susceptor 2 is raised to a processing position. Then, the gate valve 12 is closed, and the interior of the chamber 1 is maintained at a predetermined reduced pressure, and the temperature of the susceptor 2 (substrate temperature) is controlled to 300 to 500°C, for example, 450°C, by the heater 21.

[0053] In this state, the SiC film deposition process in ST2, the oxidation process in ST3, and the plasma process in ST4 are performed as shown in Fig. 4. Fig. 4 is a chart showing the gas supply, pressure, and APC opening degree when the SiC film deposition process in ST2, the oxidation process in ST3, and the plasma process in ST4 are performed.

[0054] In ST2, a SiC film is formed by ALD, which repeats the steps of supplying TMSA gas (ST2-1), purging the chamber 1 (removing residual gas) (ST2-2), supplying DS gas (ST2-3), and purging the chamber (removing residual gas) (ST2-4). At this time, the number of ALD cycles is set to x cycles, and the SiC film is formed to a given thickness.

[0055] In the ALD of ST2, the on-off valves 83 and 84 are left open to supply Ar gas at a constant rate from the first Ar gas supply source 53 and the second Ar gas supply source 54, while the on-off valves 81 and 82 are operated at high speed. During purging, both the on-off valves 81 and 82 are closed. This allows the supply of TMSA gas and DS gas to be alternated, with purging in between. The TMSA gas and DS gas are temporarily stored in the storage tanks 77 and 78 (Filled) and then pressurized before being supplied. After the supply, the storage tanks 77 and 78 are returned to the Filled state.

[0056] Examples of conditions other than temperature during ST2 are as follows: Ar gas flow rate (total): 0 to 1500 sccm TMSA gas flow rate: 30 to 200 sccm DS gas flow rate: 30 to 350 sccm ST2-1 time: 1~6 seconds ST2-2 and ST2-4 time: 5 to 15 seconds ST2-3 time: 0.05~1 sec Pressure: 1266~3000Pa

[0057] After performing ST2 by x cycles of ALD, the automatic pressure control valve (APC) is fully opened to vacuum purge the chamber 1, and pressure is adjusted with Ar gas, followed by oxidation treatment in ST3.

[0058] The oxidation treatment in ST3 is performed by opening the on-off valve 85 and supplying O2 gas as an oxygen-containing gas from the O2 gas supply source 55 while controlling the temperature (substrate temperature) of the susceptor 2 at 300 to 500°C, for example, 450°C, and while continuing to supply Ar gas. Thereafter, the on-off valve 85 is closed and purging is performed with Ar gas. The SiC-based film formed on the substrate W is oxidized by this oxidation treatment to become a SiOC-based film. Then, x cycles of SiC-based film formation and oxidation treatment are repeated y cycles to obtain a SiOC-based film with a given thickness.

[0059] Examples of conditions other than temperature when performing ST3 are as follows: Ar gas flow rate (total): 600 to 1500 sccm O2 gas flow rate: 250 to 2000 sccm Time: 2~8sec Pressure: 1266~3000Pa

[0060] After y cycles of ST2 and ST3 using ALD are performed, plasma treatment in ST4 is performed. The plasma treatment in ST4 is performed by opening the on-off valve 86, supplying H gas from the H gas supply source 55, and applying high-frequency power (RF power) from the high-frequency power supply 91 while controlling the temperature (substrate temperature) of the susceptor 2 to 300 to 500°C, for example, 450°C, and continuing to supply Ar gas. Thereafter, the on-off valve 86 is closed, and purging with Ar gas is performed. This plasma treatment modifies the SiOC-based film formed on the substrate W.

[0061] Then, by repeating x cycles of SiC-based film formation and oxidation treatment for y cycles, followed by z cycles of plasma treatment, a modified SiOC-based film having a given film thickness is obtained.

[0062] Examples of conditions other than temperature when performing ST4 are as follows: Ar gas flow rate (total): 0 to 9000 sccm H2 gas flow rate: 1000 to 4000 sccm RF power: 50~400W RF time: 1~8sec Pressure: 266~2666Pa

[0063] The number of cycles x used to form the SiC-based film corresponds to the thickness of the SiC-based film before the oxidation treatment in ST3 and indicates the frequency of the oxidation treatment. The number of cycles y used to form the SiOC-based film corresponds to the thickness of the SiC-based film before the plasma treatment in ST4 and indicates the frequency of the H plasma treatment. The frequency of the oxidation treatment can be adjusted by changing x, and the frequency of the modification of the SiOC-based film by the H plasma treatment can be adjusted by changing y. Thus, by controlling the frequency of the oxidation treatment by x and the frequency of the plasma modification by y, the composition of the SiOC-based film (O concentration in the film) can be controlled. The composition of the SiOC-based film (O concentration in the film) can also be controlled by changing the conditions of the oxidation treatment (time, gas flow rate, etc.) and the conditions of the H plasma treatment (time, etc.). The wet etching resistance (chemical treatment resistance), which changes depending on the composition (O concentration in the film) of the SiOC-based film, and electrical properties such as the k value and leakage characteristics can also be controlled.

[0064] Furthermore, the film formation apparatus 100 allows the formation of a SiC film in ST2, the oxidation treatment in ST3, and the plasma treatment in ST4 to be performed consecutively in the same chamber, thereby enabling the formation of a SiOC-based film with high controllability of film composition and film properties at high throughput.

[0065] <Experimental Example> Next, experimental examples that support the above-described embodiments will be described. Here, a bare-Si substrate was prepared as the substrate. Using the film formation apparatus shown in Figure 3, a SiC-based film was formed on the substrate by ALD using TMSA gas and DS gas (ST2), oxidation treatment using O2 gas (ST3), and H2 plasma treatment using H2 gas and Ar gas (ST4), in the sequence shown in Figure 4, to form a SiOC film. The conditions were as described above, with x and y being varied.

[0066] Figure 5 shows the relationship between the number of cycles x during SiC-based film deposition, corresponding to the frequency of oxidation treatment, and the film composition. The number of cycles y, corresponding to the frequency of H2 plasma treatment, is also varied. The film composition without H2 plasma treatment is also shown. Note that this figure only considers Si, O, and C, and shows the ratio of each component to their total in % (at%); other components such as H are not considered. This is also true for the following figures. As shown in this figure, the smaller x, i.e., the higher the frequency of oxidation treatment, the higher the O concentration in the film, indicating that the film composition can be controlled by the frequency of oxidation treatment. Furthermore, when comparing with and without H2 plasma treatment, it can be seen that the O concentration in the film decreases with H2 plasma treatment at the same frequency of oxidation treatment.

[0067] Figure 6 shows the relationship between the thickness and composition of the SiC-based film after one oxidation treatment, with x in Figure 5 replaced with film thickness, since the thickness of the SiC-based film after one ALD cycle is 0.32 Å. The smaller the thickness of the SiC-based film during oxidation treatment, the higher the O concentration in the film.

[0068] Figure 7 shows the relationship between the number of cycles x before oxidation during SiC-based film deposition and DHF resistance, corresponding to the frequency of oxidation treatment. As in Figure 5, the number of cycles y, corresponding to the frequency of H plasma treatment, is also varied. Results are also shown for the case without H plasma treatment. As shown in this figure, DHF resistance is low without H plasma treatment after oxidation, and decreases with increasing x (increasing the frequency of oxidation treatment). In contrast, performing H plasma treatment after oxidation improves DHF resistance. When x is 3 or greater, i.e., when the SiC-based film thickness before oxidation is 0.9 Å or greater, the DHF wet etching rate (WER) is nearly zero. However, when the frequency of oxidation treatment increases and x is 2 or less, i.e., when the SiC-based film thickness before oxidation is 0.6 Å or less, DHF resistance remains low even with H plasma treatment.

[0069] Figure 8 shows the relationship between the number of cycles x during SiC-based film formation, which corresponds to the frequency of oxidation treatment, and the k value and leakage value of the film. Here, the number of cycles y, which corresponds to the frequency of H2 plasma treatment, is also changed. As shown in this figure, without H2 plasma treatment, k is 3.9 at x = 10 (oxidation treatment every 3.2 Å of SiC-based film thickness), and the leakage value is 1 × 10 at 2 MV / cm. -8 A / cm 2 However, when H2 plasma treatment was performed (y=1), the k value was over 4.5 and the leakage value was 1×10 -8 A / cm 2 On the other hand, even when H2 plasma treatment is performed, if x is 5 or less, that is, the thickness of the SiC-based film before oxidation treatment is 1.6 Å or less, the k value is 4.5 or less and the leakage value is 1 × 10 -8 A / cm 2 It was confirmed that the following favorable values ​​were obtained:

[0070] Figure 9 shows the relationship between the number of cycles y (corresponding to the frequency of H plasma treatment) before oxidation treatment during SiC-based film deposition and the film composition when the number of cycles x (corresponding to the frequency of oxidation treatment) before oxidation treatment is fixed at 5. Here, y is varied between 2 and 8, with the H plasma treatment time set to 1 second. For y = 8, the film composition was also determined for a 4-second H plasma treatment. The film composition without H plasma treatment is also shown. Note that x = 5 corresponds to a film thickness of 1.6 Å before oxidation treatment. The SiOC-based film deposition rate at x = 5 is 0.47 Å / cycle. The SiOC-based film thicknesses before H plasma treatment at y = 2, 4, and 8 are 4.6 Å, 9.3 Å, and 18.7 Å, respectively. As shown in this figure, the O concentration in the film increases with increasing y, i.e., the frequency of H plasma treatment decreases. This confirms that the film composition can be controlled by the frequency of H plasma treatment.

[0071] Figure 10 shows the relationship between the number of cycles y, corresponding to the frequency of H2 plasma treatment, and the DHF resistance of the film when the number of cycles before oxidation treatment during SiC-based film deposition, x, corresponding to the frequency of oxidation treatment, is fixed at 5. As in Figure 9, y was varied between 2 and 8, with the H2 plasma treatment time set to 1 second. For y = 8, the H2 plasma treatment time was set to 4 seconds. The results without H2 plasma treatment are also shown. As shown in this figure, H2 plasma treatment improves DHF resistance, but the larger y, i.e., the lower the frequency of H2 plasma treatment, the lower the DHF resistance (higher WER). At y = 8 (SiOC-based film thickness 18.7 Å), the WER was 17 Å / min. At y=4 (SiOC film thickness 9.3 Å) and y=2 (SiOC film thickness 4.6 Å), the WER was 7 Å / min and 3 Å / min, respectively, which was lower than the standard of 10 Å / min and showed good DHF resistance. Furthermore, at y=8, the WER improved to 4 Å / min by increasing the H2 plasma treatment time from 1 sec to 4 sec.

[0072] Figure 11 shows the relationship between the number of cycles y, which corresponds to the frequency of H2 plasma treatment, and the film's k value and leakage value when the number of cycles x before oxidation treatment during SiC-based film deposition, which corresponds to the frequency of oxidation treatment, is fixed at 5. As in Figure 9, y was varied between 2 and 8, and the H2 plasma treatment time was set to 1 second. For y = 8, the H2 plasma treatment time was set to 4 seconds, and the k value and leakage value were similarly determined. The results for the case without H2 plasma treatment are also shown. As shown in this figure, when y = 2 (SiOC-based film thickness 4.6 Å), the k value and leakage value increased compared to when H2 plasma treatment was not performed, but the k value was below 4.5 and the leakage value was 1 × 10. -8 A / cm 2 In addition, when y is 4 or more (SiOC film thickness is 9.3 Å or more), the leakage value is 1×10 -8 A / cm 2 The k value is reduced to less than 4 while still satisfying the following: When the H2 plasma treatment time is increased from 1 second to 4 seconds at y=8, the leakage value is further reduced.

[0073] Next, based on the above results, the relationship between the oxygen concentration in the film and the film characteristics was examined. Figure 12 shows the relationship between the O concentration and the WER in 50% DHF for SiOC films deposited under the various conditions described above. Figure 13 shows an enlarged view of a portion of Figure 12. As shown in these figures, H plasma treatment can reduce the WER in 50% DHF to 10 Å / min or less when the O concentration of the film is 42% or less. Even with H plasma treatment, the WER is high, exceeding 27 Å / min, when the O concentration is 49% or more. Furthermore, when the H plasma treatment frequency is low (y = 8), the WER is high at 17 Å / min even with an O concentration of 42% when x = 5 (corresponding to a SiC film thickness of 1.6 Å) and the treatment time is 1 second. This is likely due to insufficient film modification due to the low H plasma treatment frequency. On the other hand, even when the O concentration is 42% and y = 8, the WER is also low at 10 Å / min when the treatment time is 4 seconds. Although no experiments were performed at O ​​concentrations lower than 26%, it is believed that high DHF resistance can be obtained even at O ​​concentrations lower than 26% up to about 10%.

[0074] Fig. 14 is a graph showing the relationship between the O concentration and the k value in the SiOC films formed under the various conditions described above. Fig. 15 is a graph showing the relationship between the O concentration and the leakage value in the SiOC-based films formed under the various conditions described above. As shown in these graphs, when the O concentration of the SiOC-based film is low, the k value and the leakage value tend to decrease. Generally, when the O concentration is 34% or more (including the case where H2 plasma treatment is not performed), the k value is 4.5 or less and the leakage value is 1.0 x 10 -8 A / cm 2 The following preferable values ​​are obtained. When x is fixed at 5 and y is changed from 2 to 8, the k value becomes 4.0 or less when the O concentration is 35 to 42%. When the O concentration is 49% or more, the leakage value becomes 1.0 × 10 -9 A / cm 2 When x = 5 and y = 8 and the H2 plasma treatment time is increased to 4 seconds, the O2 concentration is 42% and the -12 A / cm 2 Therefore, extremely low leakage characteristics of the following can be obtained.

[0075] <Other applications> Although the embodiments have been described above, the disclosed embodiments should be considered to be illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0076] For example, in the above embodiment, an organic compound gas having unsaturated carbon bonds is mainly used as the carbon-containing gas serving as the carbon precursor, and a silane-based compound is mainly used as the silicon-containing gas serving as the silicon precursor, but this is not limiting. Also, in the above embodiment, an example is shown in which ALD is mainly used to form a SiC-based film, but this is not limiting.

[0077] Furthermore, the film formation apparatus is not limited to the structure of the film formation apparatus 100 of the above embodiment, and various structures can be used. Furthermore, in the above embodiment, an example was shown in which a single-wafer type film formation apparatus was used as the film formation apparatus 100, but a batch type film formation apparatus that processes multiple substrates may also be used. As a batch type film formation apparatus, for example, a vertical type apparatus that carries multiple substrates stacked vertically into a reaction tube and processes them can be used.

[0078] In the above embodiment, an example was shown in which the deposition of the SiC-based film, the oxidation treatment of the SiC-based film, and the H plasma treatment of the SiOC film were all performed in the chamber 1 of the film deposition apparatus 100, but this is not limiting, and any or all of these may be performed in separate apparatuses. In this case, it is preferable to connect the chambers of each apparatus to a vacuum transfer chamber so that the deposition of the SiC-based film, the oxidation treatment of the SiC-based film, and the H plasma treatment of the SiOC film are performed in situ.

[0079] Furthermore, the frequency of the oxidation treatment (thickness of the SiC-based film before the oxidation treatment) and the frequency of the H gas plasma treatment (thickness of the SiC-based film before the H plasma treatment) may be constant or may be changed.

[0080] Furthermore, in the above embodiment, a semiconductor substrate (semiconductor wafer) is used as an example of the substrate, but the present invention is not limited to this and can be applied to any type of substrate. [Explanation of symbols]

[0081] 1; Chamber 2; susceptor 3. Shower head 4. Exhaust section 5. Gas supply mechanism 6. Plasma generation mechanism 7; Control unit W; substrate

Claims

1. A method for forming a SiOC-based film, comprising: providing a substrate; forming a SiC-based film on the substrate using a carbon precursor made of a carbon-containing gas and a silicon precursor made of a silicon-containing gas; performing an oxidation treatment on the SiC-based film on the substrate to form a SiOC-based film; The SiOC-based film on the substrate is ２ a step of treating with a plasma of a gas containing a gas; and the step of forming the SiC-based film is performed until the SiC-based film reaches a predetermined thickness; performing the step of forming the SiC-based film and the step of forming the SiOC-based film by the oxidation treatment one or more times until the SiOC-based film reaches a predetermined film thickness; The operation of forming the SiOC-based film to the predetermined film thickness and the step of treating with the plasma are carried out once or a plurality of times; The film forming method, wherein the step of forming the SiC-based film uses an organic compound gas as the carbon precursor, and the organic compound gas has a triple bond between carbon atoms.

2. 2. The film forming method according to claim 1, wherein the step of forming the SiC-based film uses a silane-based compound gas as the silicon precursor.

3. 3. The film forming method according to claim 2, wherein the organic compound gas used as the carbon precursor is any one of bistrimethylsilylacetylene (BTMSA), trimethylsilylacetylene (TMSA), trimethylsilylmethylacetylene (TMSMA), and bischloromethylacetylene (BCMA), and the silane compound used as the silicon precursor is disilane.

4. The film forming method according to claim 3 , wherein the step of forming the SiC-based film is carried out at a temperature of 500° C. or less.

5. 4. The film forming method according to claim 3, wherein the given film thickness of the SiC-based film is in the range of 0.9 to 3.2 Å.

6. 6. The film forming method according to claim 1, wherein the SiC-based film is formed by ALD, which sequentially supplies the carbon precursor and the silicon precursor to the substrate.

7. 7. The film forming method according to claim 6, wherein the number of cycles during film formation by ALD is 3 to 10.

8. 6. The film forming method according to claim 1, wherein the oxidation treatment is performed by a thermal reaction with an oxygen-containing gas or by using plasma of an oxygen-containing gas.

9. The oxygen-containing gas is O ２ Gas, H ２ O gas, O ３ Gas, H ２ O ２ 9. The film forming method according to claim 8, wherein the gas is any one of the following gases:

10. The H ２ The step of treating the SiOC-based film with plasma of a gas containing H ２ As the gas containing gas, H ２ Gas alone or H ２ The film forming method according to claim 1 , wherein a mixed gas of a gas and an inert gas is used.

11. 11. The film forming method according to claim 10, wherein the given film thickness of the SiOC-based film is in the range of 0.4 to 18.7 Å.

12. The H ２ 11. The film forming method according to claim 10, wherein the step of treating with plasma of a gas containing a gas controls the degree of modification of the SiOC-based film by adjusting the treatment time.

13. forming a SiC-based film; oxidizing the SiC-based film on the substrate to form a SiOC-based film; and oxidizing the SiC-based film on the substrate with H ２ The film forming method according to claim 1 , wherein the step of treating with plasma of a gas containing the gas is carried out in the same chamber.

14. forming a SiC-based film; oxidizing the SiC-based film on the substrate to form a SiOC-based film; and oxidizing the SiC-based film on the substrate with H ２ The film forming method according to claim 1 , wherein the step of treating with plasma of a gas containing the gas is carried out at the same temperature as the step of treating with plasma of the gas containing the gas.

15. 6. The film forming method according to claim 1, wherein the SiOC-based film formed on the substrate has a wet etching rate with dilute hydrofluoric acid of 10 Å / min or less.

16. 6. The film forming method according to claim 1, wherein the SiOC-based film formed on the substrate has a relative dielectric constant of 4.5 or less.

17. The SiOC-based film formed on the substrate has a leakage value of 10×10 at 2 MV / cm. －８ A / cm ２ The film forming method according to any one of claims 1 to 5, wherein:

18. A film forming apparatus for forming a SiOC-based film, a container for accommodating a substrate; a heating mechanism for heating the substrate within the container; The container contains at least a carbon precursor made of a carbon-containing gas, a silicon precursor made of a silicon-containing gas, an oxygen-containing gas, and H ２ a gas supply mechanism for supplying a gas; an exhaust mechanism for exhausting the inside of the container; a control unit; The control unit placing a substrate in the container; forming a SiC-based film on the substrate using a carbon precursor made of a carbon-containing gas and a silicon precursor made of a silicon-containing gas; performing an oxidation treatment on the SiC-based film on the substrate to form a SiOC-based film; The SiOC-based film on the substrate is ２ a step of treating with a plasma of a gas containing a gas; and the step of forming the SiC-based film is performed until the SiC-based film reaches a predetermined thickness; performing the step of forming the SiC-based film and the step of forming the SiOC-based film by the oxidation treatment one or more times until the SiOC-based film reaches a predetermined film thickness; controlling the gas supply mechanism, the heating mechanism, and the exhaust mechanism so that the operation of forming the SiOC-based film to the given film thickness and the step of treating with plasma are performed once or a plurality of times; In the step of forming the SiC-based film, an organic compound gas is used as the carbon precursor, and the organic compound gas has a triple bond between carbon atoms.

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