Method and apparatus for modifying SiOC-based films

Abstract

The present invention provides a method and apparatus for modifying SiOC-based films to improve their etching resistance and electrical properties. [Solution] The method for modifying an SiOC-based film comprises the steps of preparing a substrate on which an SiOC-based film is formed, and treating the SiOC-based film with a plasma of H2 gas alone or a mixture of H2 gas and an inert gas. The plasma treatment is performed to remove mainly the H component from the SiOC-based film, thereby densifying the SiOC-based film and improving its wet etching resistance and electrical properties.

Description

[Technical Field]

[0001] This disclosure relates to a method and apparatus for modifying an OSiOC-based film. [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 using a gas of a carbon precursor containing an organic compound having unsaturated carbon bonds and a gas of a silicon precursor containing a silicon compound, as a silicon-containing film suitable for hard masks.

[0003] On the other hand, SiOC films are known as insulating silicon-containing films with a low 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 the steps of forming a first film containing Si, O, and C using a silicon compound having Si-O bonds as a raw material gas, and 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 Publication No. 2022-67559 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] This disclosure provides a method and apparatus for modifying a SiOC-based film to improve its etching resistance and electrical properties. [Means for solving the problem]

[0006] A method for modifying an SiOC-based film according to one aspect of the present disclosure comprises the steps of preparing a substrate on which an SiOC-based film is formed, and treating the SiOC-based film with a plasma of H2 gas alone or a mixture of H gas and an inert gas, wherein the plasma treatment is performed to remove mainly the H component from the SiOC-based film, thereby densifying the SiOC-based film and improving its wet etching resistance and electrical properties. [Effects of the Invention]

[0007] This disclosure provides a method and apparatus for modifying a SiOC film to improve its etching resistance and electrical properties. [Brief explanation of the drawing]

[0008] [Figure 1] This is an example of a flowchart illustrating a film deposition method according to one embodiment. [Figure 2] This diagram shows the flow chart for depositing a SiC-based film of ST2 using ALD (Advanced Laser Development). [Figure 3] This is a cross-sectional view showing an example of a film deposition apparatus used to carry out a film deposition method according to one embodiment. [Figure 4] This chart shows the gas supply, pressure, and APC opening during the SiC film deposition process (ST2), oxidation process (ST3), and plasma treatment (ST4). [Figure 5] This figure shows the relationship between the number of cycles x during SiC film deposition, which corresponds to the frequency of oxidation treatment, and the film composition. [Figure 6] Figure 5 shows the relationship between the film thickness and film composition of a SiC-based film after one oxidation treatment, with x replaced by film thickness. [Figure 7] This figure shows the relationship between the number of cycles x required for oxidation treatment during SiC film deposition, corresponding to the frequency of oxidation treatment, and DHF resistance. [Figure 8] This figure shows the relationship between the number of cycles x during SiC film deposition, which corresponds to the frequency of oxidation treatment, and the k value and leak value of the film. [Figure 9] It is a diagram showing the relationship between the cycle number y corresponding to the frequency of H2 plasma treatment and the film composition when the cycle number x until the oxidation treatment during the formation of the SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 10] It is a diagram showing the relationship between the cycle number y corresponding to the frequency of H2 plasma treatment and the DHF resistance of the film when the cycle number x until the oxidation treatment during the formation of the SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 11] It is a diagram showing the relationship between the cycle number y corresponding to the frequency of H2 plasma treatment and the k value and leakage value of the film when the cycle number x until the oxidation treatment during the formation of the SiC-based film corresponding to the frequency of the oxidation treatment is fixed at 5. [Figure 12] It is a diagram showing the relationship between the O concentration and the WER for 50% DHF in the SiOC film formed under various conditions. [Figure 13] It is a diagram showing an enlarged view of a part of FIG. 12. [Figure 14] It is a diagram showing the relationship between the O concentration and the k value in the SiOC film formed under various conditions. [Figure 15] It is a diagram showing the relationship between the O concentration and the leakage value in the SiC-based film formed under various conditions.

Embodiments for Carrying Out the Invention

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

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

[0011] As shown in Figure 1, the formation of the SiC-based film ST2 is carried out until a given thickness is reached. This process of forming the SiC-based film by oxidation treatment ST3 is repeated once or multiple times until the SiC-based film reaches a given thickness. Subsequently, the formed SiC-based film is subjected to H2 plasma treatment ST4 to modify the SiC-based film. The process of forming the SiC-based film until a given thickness is reached (the process of performing ST2 and ST3 once or multiple times) and the process of performing H2 plasma treatment ST4 are repeated once or multiple times until the modified SiC-based film reaches a given thickness.

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

[0013] In ST2, a SiC-based film is formed by using a carbon precursor and a silicon precursor and reacting them on a substrate. The SiC-based film may contain impurities and additives in addition to SiC.

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

[0015] Silicon precursors consist of silicon-containing gases. Examples of silicon-containing gases include compounds having a Si-containing skeleton and side chains bonded to that skeleton. Examples of skeletons include Si-Si, Si-C, Si-N, and Si-O. Examples of side chains include hydrogen atoms, halogens, alkyl groups with 5 or fewer carbon atoms, carbon double or triple bonds, and groups whose bonding site to the Si in the skeleton is Si, C, N, or O. Examples of silicon-containing gases constituting silicon precursors include silane compound gases. Specific examples include disilane, monosilane, trisilane, and dichlorosilane. Organic silane compound gases such as aminosilane may also be used.

[0016] The deposition of SiC-based films of ST2 can be performed using ALD (Atomic Layer Deposition), which sequentially supplies carbon and silicon precursors. Alternatively, it may be performed using CVD (Chemical Vapor Deposition), which simultaneously supplies carbon and silicon precursors. Both methods involve thermal reactions. By using ALD, SiC films can be deposited at low temperatures with good controllability through thermal reactions without the use of plasma. Furthermore, by using an organic compound gas containing unsaturated carbon bonds as the carbon precursor, the temperature can be lowered even further, enabling film deposition at temperatures below 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, film formation can be achieved at a low temperature of 500°C or less through the following mechanism, as described in Patent Document 2.

[0018] Disilane undergoes thermal decomposition when heated to around 400°C, generating SiH2 radicals with unpaired electrons on the Si atoms. These SiH2 radicals are polarized into σ+ and σ-. It is hypothesized that the positively polarized σ+ portion acts as an electrophile, attacking the π bond of the unsaturated bond in the triple-bonded organic compound gas, decomposing the triple-bonded organic compound gas. The carbon in the triple bond then reacts with the silicon in the SiH2 radical to form a Si-C bond. Since the π bond in the triple bond has a weaker bonding force than the σ bond, when the SiH2 radical attacks the π bond, the thermal reaction proceeds sufficiently even at substrate temperatures below 500°C, generating a Si-C bond.

[0019] It should be noted that 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, when an organic compound gas containing unsaturated carbon bonds, particularly triple bonds, is used as the carbon precursor, it is thought that a similar mechanism can be used to lower the film deposition temperature.

[0020] When forming a SiC-based film of ST2 by ALD, the 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, as shown in Figure 2. By supplying a carbon precursor in ST2-1, the carbon precursor is adsorbed onto the substrate, and excess residual gas is removed in ST2-2. Then, by supplying a silicon precursor to the substrate in ST2-3, the carbon precursor adsorbed on the substrate reacts with the silicon precursor to form a SiC unit film, and excess residual gas is removed in ST2-4. By repeating ST2-1 to ST2-4 multiple times, a SiC-based film of the desired thickness is obtained.

[0021] The ST3 oxidation treatment involves depositing a SiC-based film of a given thickness on the substrate in ST2, then supplying an oxygen-containing gas to oxidize the SiC-based film to form a SiOC-based film. Semiconductor devices require insulating silicon-containing films with low k values ​​and high etching resistance (chemical treatment resistance), and SiOC-based films are silicon-containing films that possess such characteristics. A SiOC-based film of a given thickness is obtained by performing the SiC-based film deposition and oxidation treatment once or multiple times. The SiOC-based film may contain impurities and additives in addition to SiOC.

[0022] O2 gas, H2O gas, O3 gas, and H2O2 gas can be used as the oxygen-containing gas for the oxidation treatment. This oxidation treatment can be carried out by a thermal reaction. Alternatively, an oxygen-containing gas plasma may be used. The temperature during the oxidation treatment is not particularly limited as long as the SiC-based film is oxidized, but it can be carried out at the same temperature as the temperature used for depositing the SiC-based film of ST2.

[0023] The composition of the SiC film (oxygen concentration in the film) can be controlled by adjusting the film thickness of the SiC film before the ST3 oxidation treatment (the film thickness between oxidation treatments). The film thickness of the SiC film during the ST3 oxidation treatment can also be understood as the frequency of oxidation treatment; the thinner the film thickness, the higher the frequency of oxidation treatment and the higher the oxygen concentration in the film. The film thickness of the SiC film during 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 film during oxidation treatment within this range, the oxygen concentration in the film can be set to 26 to 42 at%, resulting in good wet etching resistance, as will be described later.

[0024] When film deposition is performed by ALD, the film 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 deposition temperature is around 450°C, and one ALD cycle corresponds to a film thickness of approximately 0.32 Å. Therefore, the aforementioned film thickness range of 0.9 to 3.2 Å corresponds to 3 to 10 cycles.

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

[0026] The plasma treatment with H2 gas in ST4 modifies the SiC-based film formed by the oxidation treatment in ST3. As mentioned above, when forming SiC-based films, carbon-containing gases and silicon-containing gases are used as carbon precursors and silicon precursors, respectively. Generally, organic compound gases are used as carbon-containing gases and silane-based gases are used as silicon-containing gases, so SiC-based films contain a large amount of H. Therefore, in ST4, the SiC-based film formed by the oxidation treatment in ST3 is subjected to plasma treatment with a gas containing H2 gas (hereinafter simply referred to as "H2 plasma treatment") to modify the film by removing mainly the H component. This modification treatment densifies the SiC-based film, changes its composition, and improves its wet etching resistance (chemical treatment resistance).

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

[0028] The modification effect can be controlled by adjusting the film thickness of the SiOC-based film before H2 plasma treatment. The film thickness of the SiOC-based film during H2 plasma treatment of ST4 can also be understood as the frequency of H2 plasma treatment; the thinner the film thickness, the higher the frequency of H2 plasma treatment. By controlling the frequency of H2 plasma treatment, the film composition can be controlled, and consequently, the wet etching resistance (chemical treatment resistance) and electrical properties (k value, leakage characteristics) can be controlled. For example, lowering the frequency of H2 plasma treatment tends to increase the O concentration in the film, and tends to decrease the 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. When the thickness of the SiOC-based film before H2 plasma treatment is thin (i.e., when H2 plasma treatment is performed frequently), the k value tends to be higher. On the other hand, when the thickness of the SiOC-based film before H2 plasma treatment is thick (i.e., when H2 plasma treatment is performed frequently), the modification effect by H2 plasma treatment tends to be smaller.

[0030] Furthermore, the modification effect can be controlled by adjusting the processing conditions of the H2 plasma treatment. For example, by increasing the processing time of the H2 plasma treatment, the modification effect can be enhanced, and even if the thickness of the SiOC-based film before plasma treatment remains the same, the wet etching resistance and leak characteristics can be improved.

[0031] While 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. Performing them in the same chamber allows ST2 to ST4 to be performed without substrate transport, enabling high throughput.

[0032] As described above, according to this embodiment, the film composition of the SiOC-based film, as well as film properties such as wet etching resistance and electrical properties, can be easily controlled by a simple method of adjusting the frequency and conditions of oxidation treatment and H2 plasma treatment.

[0033] Furthermore, by adjusting the film thickness and oxidation conditions of the SiC-based film during oxidation treatment, and the film thickness and time of the SiC-based film during H2 plasma treatment, it is possible to form SiC-based films with desired film composition and characteristics. For example, the oxygen concentration of the SiC-based film can be controlled to 10-60 at%, and within this range, by setting the oxygen concentration to 10-45 at%, good wet etching resistance can be achieved. In particular, by setting the oxygen concentration to 26-42 at%, the wet etching rate against dilute hydrofluoric acid (DHF) can be set to 10 Å / min or less. Also, by setting the oxygen concentration to 34 at% or higher, the k value can be 4.5 or less, and the leak characteristics (leak value) at 2 MV / cm can be 10 × 10⁻¹⁰. -8 A / cm 2 The following can be achieved. Furthermore, by optimizing the frequency of oxidation treatment, the frequency or time of H2 plasma treatment, the k value can be reduced to 4 or less, and the leak value to 10 × 10 -9 A / cm 2 The following can be achieved. Furthermore, by setting the oxygen concentration to 34-45 at%, the wet etching characteristics, k-value, and leak characteristics can all be improved.

[0034] <Film forming equipment> Next, an example of a film deposition apparatus used for forming the SiC-based film described above will be explained. Here, a single-wafer film deposition apparatus is shown that uses a semiconductor wafer (hereinafter simply referred to as "wafer") as the substrate and deposits a SiC-based film on the wafer by ALD, while also performing oxidation treatment and plasma treatment. In addition, trimethylsilylacetylene (TMSA) gas is used as the carbon precursor, disilane (DS) gas as the silicon precursor, O2 gas as the oxygen-containing gas, and Ar gas as the inert gas.

[0035] Figure 3 is a cross-sectional view showing an example of a film deposition apparatus used for forming SiOC-based films. As shown in Figure 3, the film deposition 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 7.

[0036] Chamber 1 is made of a metal such as aluminum and has a substantially cylindrical shape. An inlet / outlet 11 for loading and unloading wafers W is formed in the side wall of Chamber 1, and the inlet / outlet 11 can be opened and closed by a gate valve 12. An annular exhaust duct 13 with a rectangular cross-section is provided on top of the main body of Chamber 1. A slit 13a is formed along the inner circumference of the exhaust duct 13. An exhaust port 13b is also formed in the outer wall of the exhaust duct 13. A top wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of Chamber 1. An insulating ring 16 is fitted around the outer circumference of the top wall 14, and the space between the insulating ring 16 and the exhaust duct 13 is airtightly sealed by a seal ring 15.

[0037] The susceptor 2 is for horizontally supporting the wafer W within the chamber 1. The susceptor 2 is disc-shaped, corresponding to the size of the wafer W, and is supported by a support member 23. This susceptor 2 is made of a ceramic material such as aluminum nitride (AlN) or a metallic material such as aluminum or nickel-based alloy, and has a heater 21 embedded inside for heating the wafer W. The heater 21 is powered by a heater power supply (not shown) and generates heat. The output of the heater 21 is controlled by the temperature signal of a thermocouple (not shown) provided near the wafer mounting surface on the upper surface of the susceptor 2, thereby controlling the wafer W to a predetermined temperature.

[0038] The susceptor 2 is provided with a cover member 22 made of ceramics such as alumina, which covers the outer peripheral region of the wafer mounting surface and the sides of the susceptor 2.

[0039] The support member 23 that supports the susceptor 2 extends downward from the center of the bottom surface of the susceptor 2 through a hole formed in the bottom wall of the chamber 1, and its lower end is connected to the lifting mechanism 24. The lifting mechanism 24 allows the susceptor 2 to move up and down via the support member 23 between the processing position shown in Figure 3 and the transport position below it, indicated by the dashed line, where wafer transport is possible. A flange member 25 is attached to the lower part of 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, which partitions the atmosphere inside the chamber 1 from the outside air and expands and contracts in accordance with the lifting and lowering movement of the susceptor 2.

[0040] Near the bottom of the chamber 1, three wafer support pins (only two are shown) are provided, protruding upward from the lifting plate 27a. The wafer support pins 27 can be raised and lowered via the lifting plate 27a by a lifting mechanism 28 located below the chamber 1, and can be inserted into through holes 2a provided in the susceptor 2 at the transport position, allowing them to protrude and retract 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 the wafer transport mechanism (not shown) and the susceptor 2.

[0041] The shower head 3 is a metal component for supplying a processing gas into the chamber 1 in a shower-like manner. It is positioned opposite the susceptor 2 and has approximately the same diameter as the susceptor 2. The shower head 3 has a main body 31 fixed to the top 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, which is provided to penetrate the center of the main body 31 and the top wall 14 of the chamber 1, is connected to this gas diffusion space 33. An annular projection 34 protruding downward is formed on the periphery of the shower plate 32, and a gas discharge hole 35 is formed on the flat surface inside the annular projection 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 an annular gap 38 is formed when the annular projection 34 and the upper surface of the cover member 22 of the susceptor 2 come into close proximity.

[0043] The exhaust unit 4 is for exhausting 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, the 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 is for supplying gas to the shower head 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 O2 gas supply source 55, and an H2 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 O2 gas supply source 55 supplies O2 gas as an oxygen-containing gas used for oxidation treatment. The H2 gas supply source 56 supplies H2 gas used for plasma treatment.

[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 O2 gas supply pipe 65, and an H2 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 supply source 53, and the second Ar gas supply pipe 64 extends from the second Ar gas supply source 54. In addition, the O2 gas supply pipe 65 extends from the O2 gas supply source 55, and the H2 gas supply pipe 66 extends from the H2 gas supply source 56.

[0046] The TMSA gas supply pipe 61 and the DS gas supply pipe 62 merge into a junction pipe 66, which is connected to the gas inlet port 36 mentioned above. In addition, the first Ar gas supply pipe 63 is connected to the TMSA gas supply pipe 61, and the second Ar gas supply pipe 64, O2 gas supply pipe 65, and H2 gas supply pipe 66 are connected to the DS gas supply pipe 62.

[0047] The TMSA gas supply piping 61 is equipped with a flow controller 71, such as a mass flow controller, a storage tank 77, and an on / off valve 81, from the upstream side. The DS gas supply piping 62 is equipped with a flow controller 72, a storage tank 78, and an on / off valve 82, from the upstream side. The first Ar gas supply piping 63 is equipped with a flow controller 73 and an on / off valve 83, from the upstream side, and the second Ar gas supply piping 64 is equipped with a flow controller 74 and an on / off valve 84, from the upstream side. The O2 gas supply piping 65 is equipped with a flow controller 75, a storage tank 79, and an on / off valve 85, from the upstream side. The H2 gas supply piping 66 is equipped with a flow controller 76 and an on / off valve 86, from the upstream side.

[0048] Furthermore, by switching the on / off valves 81, 82, 83, 84, 85, and 86, the ALD process, oxidation treatment, and plasma treatment described later can be performed. In addition, storage tanks 77, 78, and 79 temporarily store the corresponding gas and pressurize it to a predetermined pressure. In this state, the on / off valves are opened and the gas is supplied into chamber 1.

[0049] Furthermore, the purge gas is not limited to Ar gas; other inert gases such as N2 gas or noble gases other than Ar may also be used.

[0050] The plasma generation mechanism 6 includes a power supply line 91 connected to the main body 31 of the shower head 3, a matching unit 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 to the shower head 3 from the high-frequency power supply 91, a high-frequency electric field is formed between the shower head 3 and the electrode 94, and this high-frequency electric field generates a plasma of a gas containing H2 gas during plasma processing. The gas containing H2 gas may be H2 gas alone, or Ar gas may be added to H2 gas. The frequency of the high-frequency power supply 83 is preferably set to 450 kHz to 100 MHz, for example, 40 MHz is used. In addition, the plasma generation mechanism 6 may generate a plasma of an oxygen-containing gas, O2 gas, during oxidation processing.

[0051] The control unit 7 includes a main control unit consisting of a computer (CPU) that controls each component of the film deposition apparatus, such as valves, mass flow controllers, power supplies, heaters, and vacuum pumps, as well as an input device, an output device, a display device, and a storage device. The storage device stores parameters for various processes performed by the film deposition apparatus 100. The storage device also has a storage medium that stores programs, i.e., processing recipes, for controlling the processes performed by the film deposition apparatus 100. The main control unit retrieves a predetermined processing recipe stored in the storage medium and causes the film deposition apparatus 100 to perform a predetermined operation based on that processing recipe.

[0052] In the film deposition apparatus 100 configured in this way, first, the gate valve 12 is opened and the substrate W is transported into the chamber 1 via the input / output port 11 by a transport device (not shown) and placed on the susceptor 2. The transport device is retracted and the susceptor 2 is raised to the processing position. Then, the gate valve 12 is closed to maintain a predetermined reduced pressure state inside the chamber 1, and the heater 21 controls the temperature of the susceptor 2 (substrate temperature) to 300-500°C, for example, 450°C.

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

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

[0055] In the ST2 ALD, with the on / off valves 83 and 84 kept open, Ar gas is supplied 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 on / off valves 81 and 82 are closed. This allows for the alternating supply of TMSA gas and DS gas with purging in between. The TMSA gas and DS gas are initially stored (filled) in storage tanks 77 and 78, pressurized, and then supplied. After supply, storage tanks 77 and 78 are filled with gas.

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

[0057] After performing ST2 with x-cycle ALD, the automatic pressure control valve (APC) is fully opened to create a vacuum purging state inside chamber 1, and pressure adjustment is performed with Ar gas, followed by the ST3 oxidation treatment.

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

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

[0060] After performing ST2 and ST3 with ALD in a y-cycle, the ST4 plasma treatment is carried out. The ST4 plasma treatment is performed by opening the on / off valve 86, supplying H2 gas from the H2 gas supply source 55, and applying high-frequency power (RF power) from the high-frequency power supply 91, while maintaining the susceptor 2 temperature (substrate temperature) at 300-500°C, for example, 450°C, and while supplying Ar gas. After that, 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 the deposition and oxidation of a SiC-based film for x cycles and then performing a plasma treatment cycle for z cycles, a modified SiC-based film of a given thickness is obtained.

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

[0063] The number of cycles x used to deposit the SiC-based film corresponds to the film thickness of the SiC-based film before the ST3 oxidation treatment, and indicates the frequency of the oxidation treatment. Similarly, the number of cycles y used to form the SiOC-based film corresponds to the film thickness of the SiOC film before the ST4 plasma treatment, and indicates the frequency of the H2 plasma treatment. By changing x, the frequency of the oxidation treatment can be adjusted, and by changing y, the frequency of modification of the SiOC-based film by H2 plasma treatment can be adjusted. In this way, by controlling the frequency of oxidation treatment by x and the frequency of plasma modification by y, the composition of the SiOC-based film (O concentration in the film) can be controlled. Furthermore, 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 H2 plasma treatment (time, etc.). In the same way, the wet etching resistance (chemical treatment resistance) and electrical properties such as the k value and leakage characteristics, which change with the composition (O concentration in the film) of the SiOC-based film, can also be controlled.

[0064] Furthermore, the film deposition apparatus 100 allows for the continuous deposition of the SiC film ST2, the oxidation treatment ST3, and the plasma treatment ST4 in the same chamber, enabling high-throughput deposition of SiOC-based films with highly controllable film composition and properties.

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

[0066] Figure 5 shows the relationship between the number of cycles x during SiC film deposition, corresponding to the frequency of oxidation treatment, and the film composition. Here, the number of cycles y, corresponding to the frequency of H2 plasma treatment, is also varied. The film composition when H2 plasma treatment is not performed is also shown. Note that in this figure, only Si, O, and C are considered, and the ratio of each component to the sum of these is shown in % (at%), and other components such as H are not considered. The same applies to the following figures. As shown in this figure, the smaller x is, that is, 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 the presence or absence of H2 plasma treatment, it can be seen that the O concentration in the film decreases when H2 plasma treatment is performed at the same oxidation treatment frequency.

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

[0068] FIG. 7 is a diagram showing the relationship between the number of cycles x until the oxidation treatment during the formation of the SiC-based film corresponding to the frequency of the oxidation treatment and the DHF resistance. Here, similar to FIG. 5, the number of cycles y corresponding to the frequency of the H2 plasma treatment is also changed, and the results when the H2 plasma treatment is not performed are also shown. As shown in this figure, the DHF resistance is low without the H2 plasma treatment after the oxidation treatment, and the DHF resistance decreases with an increase in x (increase in the frequency of the oxidation treatment). On the other hand, by performing the H2 plasma treatment after the oxidation treatment, the DHF resistance is improved, and it can be seen that when x is 3 or more, that is, when the film thickness of the SiC-based film until the oxidation treatment is 0.9 Å or more, the wet etching rate (WER) by DHF is almost 0. However, when the frequency of the oxidation treatment increases and x is 2 or less, that is, when the film thickness of the SiC-based film until the oxidation treatment is 0.6 Å or less, it can be seen that the DHF resistance is low even with the addition of the H2 plasma treatment.

[0069] FIG. 8 is a diagram showing the relationship between the number of cycles x during the formation of the SiC-based film corresponding to the frequency of the oxidation treatment and the k value and leakage value of the film. Here, the number of cycles y corresponding to the frequency of the H2 plasma treatment is also changed. As shown in this figure, when there is no H2 plasma treatment, at x = 10 (oxidation treatment every 3.2 Å of the film thickness of the SiC-based film), k is 3.9 and the leakage value is 2 MV / cm and 1×10 -8 A / cm 2 the following good values are obtained. However, when the H2 plasma treatment is performed (y = 1), at the same x value, the k value exceeds 4.5 and the leakage value is 1×10 -8 A / cm 2 and becomes a higher value. On the other hand, even when the H2 plasma treatment is performed, when x is 5 or less, that is, when the film thickness of the SiC-based film until the oxidation treatment is 1.6 Å or less, it is confirmed that a good value with a k value of 4.5 or less and a leakage value of 1×10 -8 A / cm 2 or less can be obtained.

[0070] Figure 9 shows the relationship between the number of cycles y, which corresponds to the frequency of H2 plasma treatment, and the film composition, when the number of cycles x, which corresponds to the frequency of oxidation treatment during SiC film deposition, is fixed at 5. Here, y is varied between 2 and 8, and the H2 plasma treatment time is set to 1 sec. However, in the case of y=8, the film composition was similarly determined for the case where the H2 plasma treatment time was 4 sec. The film composition when no H2 plasma treatment is performed is also shown. Note that x=5 corresponds to a film thickness of 1.6 Å before oxidation treatment. The film deposition rate of the SiC film when x=5 is 0.47 Å / cyc., and the film thickness of the SiC film before H2 plasma treatment when y=2, 4, and 8 is 4.6 Å, 9.3 Å, and 18.7 Å, respectively. As shown in this figure, the larger y is, that is, the lower the frequency of H2 plasma treatment, the higher the O concentration in the film, confirming that the film composition can also be controlled by the frequency of H2 plasma treatment.

[0071] Figure 10 shows the relationship between the number of cycles y, which corresponds to the frequency of H2 plasma treatment, and the DHF resistance of the film, when the number of cycles x, which corresponds to the frequency of oxidation treatment during SiC film deposition, is fixed at 5. Here, as in Figure 9, the DHF resistance was similarly determined for cases where y was varied between 2 and 8, the H2 plasma treatment time was set to 1 sec, and in the case of y=8, the H2 plasma treatment time was set to 4 sec. The results for the case without H2 plasma treatment are also shown. As shown in this figure, the DHF resistance improves with H2 plasma treatment, but it can be seen that the larger y is, that is, the lower the frequency of H2 plasma treatment, the lower the DHF resistance (higher the WER). At y=8 (SiOC film thickness of 18.7 Å), the WER is 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 are lower than the standard 10 Å / min, indicating good DHF resistance. Furthermore, at y=8, increasing the H2 plasma treatment time from 1 sec to 4 sec improved the WER to 4 Å / min.

[0072] Figure 11 shows the relationship between the number of cycles y corresponding to the frequency of H2 plasma treatment, the k value of the film, and the leak value, when the number of cycles x until oxidation treatment is performed during SiC film deposition, which corresponds to the frequency of oxidation treatment, is fixed at 5. Here, as in Figure 9, the k value and leak value were similarly determined for cases where y was varied between 2 and 8, the H2 plasma treatment time was set to 1 sec, and in the case of y=8, the H2 plasma treatment time was set to 4 sec. The results for the case without H2 plasma treatment are also shown. As shown in this figure, at y=2 (SiOC film thickness of 4.6 Å), an increase in the k value and leak value is observed compared to the case without H2 plasma treatment, but the k value is 4.5 or less and the leak value is 1 × 10⁻⁶. -8 A / cm 2 The following conditions are met. Also, when y is 4 or greater (SiOC film thickness of 9.3 Å or greater), the leak value is 1 × 10⁻⁶. -8 A / cm 2 The k-value has decreased to less than 4 while maintaining the following conditions. Furthermore, when the H2 plasma processing time is increased from 1 sec to 4 sec at y=8, the leak value decreases even further.

[0073] Next, based on the above results, we investigated the relationship between the oxygen concentration in the membrane and the membrane properties. Figure 12 shows the relationship between the oxygen concentration and the WER relative to 50% DHF in SiOC films deposited under the various conditions described above. Figure 13 is an enlarged view of a portion of Figure 12. As shown in these figures, it was confirmed that by performing H2 plasma treatment, the WER relative to 50% DHF can be reduced to 10 Å / min or less when the oxygen concentration of the film is 42% or less. Even with H2 plasma treatment, the WER is high, at 27 Å / min or more, when the oxygen concentration is 49% or higher. Furthermore, when the H2 plasma frequency is low (y=8), at x=5 (corresponding to a SiC film thickness of 1.6 Å), the WER is high at 17 Å / min even with an oxygen concentration of 42% when the treatment time is 1 sec. This is thought to be because the film was not sufficiently modified due to the low frequency of H2 plasma treatment. On the other hand, even when the oxygen concentration is 42% and y=8, the WER becomes 10 Å / min or less when the treatment time is 4 sec. Although experiments were not conducted at oxygen concentrations lower than 26%, it is believed that high DHF resistance can be obtained even at concentrations lower than 26%, down to about 10%.

[0074] Figure 14 shows the relationship between O concentration and k value in SiOC films deposited under the various conditions described above. Figure 15 shows the relationship between O concentration and leak value in SiOC-based films deposited under the various conditions described above. As shown in these figures, the k value and leak value tend to decrease when the O concentration of the SiOC-based film is low. Roughly speaking, when the O concentration is 34% or higher (including cases where H2 plasma treatment is not performed), the k value is 4.5 or lower and the leak value is 1.0 × 10⁻⁶. -8 A / cm 2 The following desirable values ​​can be obtained. Furthermore, when x is fixed at 5 and y is varied from 2 to 8, the O concentration is 35-42% and the k value is 4.0 or less. Also, when the O concentration is 49% or higher, the leak value is 1.0 × 10⁻⁶. -9 A / cm 2 The following results in an H2 plasma processing time of 4 seconds when x=5 and y=8, resulting in 1.0 × 10⁻¹⁰ at an O concentration of 42%. -12 A / cm 2 The following extremely low leakage characteristics can be achieved.

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

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

[0077] Furthermore, the film deposition apparatus is not limited to the structure of the film deposition apparatus 100 in the above embodiment; various structures can be used. Also, although the above embodiment shows an example using a single-wafer type film deposition apparatus 100, a batch-type film deposition apparatus that processes multiple substrates may also be used. As an example of a batch-type film deposition apparatus, a vertical type apparatus that processes multiple substrates stacked vertically in a reaction tube 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 H2 plasma treatment of the SiOC film are all performed in the chamber 1 of the film deposition apparatus 100. However, the invention is not limited to this, 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 H2 plasma treatment of the SiOC film are performed in situ.

[0079] Furthermore, the frequency of oxidation treatment (thickness of the SiC-based film before oxidation treatment) and the frequency of H2 gas plasma treatment (thickness of the SiC-based film before H2 plasma treatment) may be constant or varied.

[0080] Furthermore, although a semiconductor substrate (semiconductor wafer) was used as an example of the substrate in the above embodiment, the application 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 modifying SiOC-based films, A step of preparing a substrate on which a SiOC-based film has been formed, H ２ Gas alone or H ２ A process involving processing with a plasma of a gas mixture, and It has, A method for modifying a SiOC-based film, wherein the plasma treatment is performed to remove mainly the H component from the SiOC-based film, thereby densifying the SiOC-based film and improving its wet etching resistance and electrical properties.

2. The method for modifying a SiOC-based film according to claim 1, wherein the SiOC-based film is formed by oxidizing a SiC film formed using an organic compound gas having triple bonds between carbon atoms as a carbon precursor.

3. The method for modifying a SiOC-based film according to claim 1 or claim 2, wherein the inert gas is Ar gas.

4. The method for modifying a SiOC-based film according to claim 3, wherein the plasma treatment is carried out at a temperature of 300 to 500°C.

5. The aforementioned plasma processing is H ２ Gas flow rate: 1000-4000 sccm Ar gas flow rate: 0-9000 sccm RF Power: 50-400W Processing time: 1-8 seconds Pressure: 266–2666 Pa A method for modifying an SiOC-based film according to claim 4, carried out under the following conditions.

6. The plasma treatment described above achieves a wet etching rate of the SiOC-based film with respect to dilute hydrofluoric acid of 10 Å / min or less, a relative permittivity of 4.5 or less, and a leak value of 10 × 10 at an applied electrolytic intensity of 2 MV / cm. －８ A / cm ２ A method for modifying a SiOC-based film according to claim 5, which is carried out as follows:

7. An apparatus for processing SiOC-based films, A chamber for housing a substrate on which a SiOC-based film has been formed, A susceptor that supports the substrate within the chamber, A heating mechanism for heating the substrate in the chamber to 300 to 500°C, H ２ Gas alone or H ２ A gas supply mechanism that supplies a mixed gas of a gas and an inert gas, In the chamber, the H ２ gas alone or H ２ a plasma generation mechanism that generates a plasma of a mixed gas of gas and an inert gas; An exhaust mechanism for exhausting the contents of the chamber, A control unit that controls the heating mechanism, the gas supply mechanism, the plasma generation mechanism, and the exhaust mechanism, It has, The aforementioned plasma generation mechanism is A shower head is provided at the top of the chamber and facing the substrate, The electrode embedded in the susceptor, The system includes a high-frequency power supply that supplies high-frequency power of 450 kHz to 100 MHz to the shower head, and generates the plasma by forming a high-frequency electric field between the shower head and the electrode. The control unit, H ２ An apparatus for processing an SiOC-based film, comprising: controlling the heating mechanism, the gas supply mechanism, the plasma generation mechanism, and the exhaust mechanism to perform processing with a gas-containing plasma, thereby removing mainly the H component from the SiOC-based film and densifying the SiOC-based film, and improving the wet etching resistance and electrical properties of the SiOC-based film.

8. The apparatus for forming a SiOC-based film according to claim 7, wherein the SiOC-based film is formed by oxidizing a SiC film formed using an organic compound gas having triple bonds between carbon atoms as a carbon precursor.

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