Method for modifying silicon oxide film, and substrate processing apparatus

Abstract

To provide a technique of improving the electric characteristic of a silicon oxide film.SOLUTION: A method for modifying a silicon oxide film in one aspect of the present disclosure includes the steps of: preparing a substrate where the silicon oxide film is formed; and modifying the silicon oxide film. The step of modifying the silicon oxide film includes the steps of: (a) exposing a surface of the silicon oxide film to plasma generated from first gas including a hydrogen-containing gas; (b) exposing the surface of the silicon oxide film to plasma generated from second gas not including the hydrogen-containing gas but including inert gas; and (c) exposing the surface of the silicon oxide film to plasma generated from third gas including a nitrogen-containing gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for modifying a silicon oxide film and a substrate processing apparatus.

Background Art

[0002] A technique is known in which a substrate having a silicon oxide film formed thereon is exposed to plasma generated from a mixed gas of hydrogen gas and argon gas and plasma generated from argon gas to modify the silicon oxide film (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of improving the electrical characteristics of a silicon oxide film.

Means for Solving the Problems

[0005] A method for modifying a silicon oxide film according to an aspect of the present disclosure includes a step of preparing a substrate having a silicon oxide film formed thereon and a step of modifying the silicon oxide film, and the step of modifying the silicon oxide film includes: (a) a step of exposing the surface of the silicon oxide film to plasma generated from a first gas containing a hydrogen-containing gas; (b) a step of exposing the surface of the silicon oxide film to plasma generated from a second gas containing an inert gas and not containing a hydrogen-containing gas; and (c) a step of exposing the surface of the silicon oxide film to plasma generated from a third gas containing a nitrogen-containing gas.

Effects of the Invention

[0006] According to the present disclosure, the electrical characteristics of a silicon oxide film can be improved.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

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Figure 10

Figure 11

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Figure 13

Modes for Carrying Out the Invention

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding members or components are denoted by the same or corresponding reference numerals, and duplicate descriptions are omitted.

[0009] 〔First Embodiment〕 (Method for Modifying Silicon Oxide Film) With reference to FIGS. 1 to 3, a method for modifying a silicon oxide film according to the first embodiment will be described. The method for modifying a silicon oxide film according to the first embodiment includes steps S11 to S15 shown in FIG. 1.

[0010] In step S11, as shown in FIG. 2(a), a silicon oxide film 102 is formed on an insulating film 101 formed on a substrate 100. The insulating film 101 is, for example, a low dielectric constant (Low-k) film. The type of the insulating film 101 is not particularly limited, and examples thereof include a SiO film, a SiN film, a SiOC film, a SiON film, and a SiOCN film. The SiO film means a film containing silicon (Si) and oxygen (O). The atomic ratio of Si to O in the SiO film is not limited to 1:1. The same applies to the SiN film, the SiOC film, the SiON film, and the SiOCN film. Step S11 includes, for example, steps S111 to S113 shown in FIG. 3.

[0011] In step S111, a metal catalyst gas is supplied to the substrate 100, and the metal catalyst gas is adsorbed on the insulating film 101. The metal catalyst gas is, for example, trimethylaluminum (TMA) gas. In step S111, the substrate 100 is heated at a low temperature, for example, 120°C or higher and 300°C or lower.

[0012] Step S112 is performed after step S111. In step S112, a silanol-containing gas is supplied to the substrate 100, and the silanol-containing gas is reacted with the metal catalyst gas adsorbed on the insulating film 101 to form a silicon oxide film 102. The silanol-containing gas is, for example, TPSOL (Tris(tert-pentoxy)silanol), TBSOL (Tris(tert-butoxy)silanol). In step S112, the substrate 100 is heated at a low temperature, for example, 120°C or higher and 300°C or lower.

[0013] Step S113 is performed after step S112. In step S113, it is determined whether steps S111 to S112 have been performed the set number of times. If the number of executions has not reached the set number of times (NO in step S113), steps S111 to S112 are performed again. If the number of executions has reached the set number of times (YES in step S113), since the film thickness of the silicon oxide film 102 has reached a predetermined film thickness with respect to the plasma treatment, the process is terminated. The set number of times in step S113 is set according to the film formation amount in order for the silicon oxide film 102 formed in step S11 to reach a predetermined film thickness. The film formation amount can be adjusted by, for example, the supply amount of the silanol-containing gas. The predetermined film thickness is, for example, 2 nm or more and 5 nm or less. In this case, in steps S12 to S15, the plasma easily acts on the entire silicon oxide film 102 in the film thickness direction formed in the immediately preceding step S11. For this reason, the silicon oxide film 102 is modified over the entire film thickness direction. On the other hand, when the film thickness of the silicon oxide film 102 formed in step S11 is larger than the predetermined film thickness, it is difficult for the modification by plasma to act on a deep position from the surface of the silicon oxide film 102 in steps S12 to S15. The set number of times in step S113 may be 1 time or 2 times or more.

[0014] Step S12 is performed after step S11. In step S12, as shown in FIG. 2(b), the surface of the silicon oxide film 102 is exposed to the plasma P1 generated from the first gas containing hydrogen gas. Thereby, impurities in the film including Si-OH bonds are removed. In step S12, when the silicon oxide film 102 is exposed to the plasma P1, hydrogen defects may be generated in the silicon oxide film 102 by the reaction between the active species contained in the plasma P1 and the silicon oxide film 102. The first gas may be used by mixing with argon gas. In step S12, the substrate 100 may be heated at a temperature higher than that in step S11. In this case, impurities in the film including Si-OH bonds are easily removed.

[0015] An example of the processing conditions in step S12 is as follows. · Flow rate of hydrogen gas: 200 sccm to 3000 sccm · Flow rate of argon gas: 600 sccm to 6000 sccm · Substrate temperature: 120 °C to 350 °C · Processing pressure: 1 Torr to 5 Torr (133 Pa to 667 Pa) · Processing time: 10 seconds to 60 seconds

[0016] Step S13 is performed after step S12. In step S13, as shown in Fig. 2(c), the surface of the silicon oxide film 102 is exposed to the plasma P2 generated from the second gas containing argon gas and not containing hydrogen gas. Thereby, the hydrogen defects generated in the silicon oxide film 102 in step S12 are removed. As a result, both the impurities in the film including Si-OH bonds and the hydrogen defects can be reduced. For this reason, it is easier to reduce the leakage current of the silicon oxide film 102 compared to the modification using only the plasma P1 or the modification using only the plasma P2. In step S13, the substrate 100 may be heated at a temperature higher than that in step S11. In this case, the hydrogen defects are easily removed. When shifting from step S12 to step S13, the plasma P2 may be switched while maintaining the plasma P1, or the plasma P2 may be generated after stopping the plasma P1.

[0017] An example of the processing conditions for step S13 is as follows. · Flow rate of argon gas: 600 sccm to 6000 sccm · Substrate temperature: 120 °C to 350 °C · Processing pressure: 1 Torr to 5 Torr (133 Pa to 667 Pa) · Processing time: 10 seconds to 60 seconds

[0018] Step S14 is performed after step S13. In step S14, it is determined whether steps S12 to S13 have been performed for the first number of times. If the number of executions has not reached the first number of times (NO in step S14), steps S12 to S13 are performed again. On the other hand, if the number of executions has reached the first number of times (YES in step S14), the process proceeds to step S15. The first number of times is set according to the film thickness of the silicon oxide film 102 formed in step S11, for example. The first number of times may be once, or may be two or more times. The first number of times is preferably from 2 to 6 times. When shifting from step S13 to step S12, the plasma P1 may be switched while maintaining the plasma P2, or the plasma P1 may be generated after stopping the plasma P2.

[0019] In step S15, as shown in FIG. 2(d), the surface of the silicon oxide film 102 is exposed to the plasma P3 generated from the third gas containing nitrogen gas. Thereby, the leakage current of the silicon oxide film 102 can be further reduced. It is considered that this is because the electrically active defects existing on the surface and inside of the silicon oxide film 102 are inactivated when the silicon oxide film 102 is exposed to the plasma P3. The third gas may contain argon gas. The third gas may contain hydrogen gas. The flow rate ratio of the nitrogen gas contained in the third gas may be 5% or more and 40% or less. In step S15, the substrate 100 may be heated at a temperature higher than that in step S11. In this case, the leakage current is likely to be reduced. When shifting from step S13 to step S15, the plasma P3 may be switched while maintaining the plasma P2, or the plasma P3 may be generated after stopping the plasma P2.

[0020] An example of the processing conditions in step S15 is as follows. · Flow rate of nitrogen gas: 200 sccm to 2000 sccm · Flow rate of argon gas: 600 sccm to 6000 sccm · Flow rate of hydrogen gas: 200 sccm to 2000 sccm · Substrate temperature: 120°C to 350°C ·Processing pressure: 1 Torr to 5 Torr (133 Pa to 667 Pa) ·Processing time: 10 seconds to 60 seconds

[0021] As described above, according to the method for modifying a silicon oxide film according to the first embodiment, there are a step of preparing a substrate 100 on which a silicon oxide film 102 is formed, and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S12, step S13, and step S15. In step S12, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S13, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas and not containing hydrogen gas. In step S15, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0022] (Processing system) Referring to FIG. 4, an example of a processing system PS for implementing the method for modifying a silicon oxide film according to the first embodiment will be described.

[0023] The processing system PS includes processing apparatuses PM1 to PM4, a vacuum transfer chamber VTM, load lock chambers LL1 to LL3, an atmospheric transfer chamber LM, load ports LP1 to LP3, and an overall control unit CU.

[0024] The processing apparatuses PM1 to PM4 are each connected to the vacuum transfer chamber VTM via gate valves G11 to G14. The processing apparatuses PM1 to PM4 are configured to be depressurized to a predetermined vacuum atmosphere inside. The processing apparatuses PM1 to PM4 accommodate a substrate W inside and perform a desired process.

[0025] The vacuum transfer chamber VTM is configured such that its interior can be depressurized to a predetermined vacuum atmosphere. In the vacuum transfer chamber VTM, a first transfer device TR1 capable of transferring the substrate W in a depressurized state is provided. The first transfer device TR1 transfers the substrate W to the processing devices PM1 to PM4 and the load lock chambers LL1 to LL3. The first transfer device TR1 has, for example, two transfer arms FK11 and FK12 that can move independently.

[0026] The load lock chambers LL1 to LL3 are each connected to the vacuum transfer chamber VTM via gate valves G21 to G23. The load lock chambers LL1 to LL3 are each connected to the atmospheric transfer chamber LM via gate valves G31 to G33. The load lock chambers LL1 to LL3 are configured such that their interiors can be switched between an atmospheric atmosphere and a vacuum atmosphere.

[0027] The interior of the atmospheric transfer chamber LM is an atmospheric atmosphere. Inside the atmospheric transfer chamber LM, for example, a downflow of clean air is formed. Inside the atmospheric transfer chamber LM, an aligner AN for aligning the substrate W is provided. The aligner AN may be provided outside the atmospheric transfer chamber LM. A second transfer device TR2 is provided in the atmospheric transfer chamber LM. The second transfer device TR2 transfers the substrate W to the load lock chambers LL1 to LL3, the load ports LP1 to LP3, and the aligner AN.

[0028] The load ports LP1 to LP3 are provided on the long side wall surface of the atmospheric transfer chamber LM. Carriers C are attached to the load ports LP1 to LP3. The carrier C includes a carrier C in which the substrate W is accommodated and an empty carrier C. The carrier C may be, for example, a FOUP (Front Opening Unified Pod).

[0029] The overall control unit CU may be, for example, a computer. The overall control unit CU includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an auxiliary storage device. The CPU operates based on a program stored in the ROM or the auxiliary storage device and controls each part of the processing system PS. For example, the overall control unit CU controls the operations of the processing devices PM1 to PM4, the first transfer device TR1, the second transfer device TR2, and the gate valves G11 to G14, G21 to G23, G31 to G33. For example, the overall control unit CU controls the operation of switching the interiors of the load lock chambers LL1 to LL3 between an atmospheric atmosphere and a vacuum atmosphere.

[0030] Next, the operation of the processing system PS will be described. First, the second transfer device TR2 takes out the substrate W from the carrier C, transports the taken-out substrate W to the aligner AN, and exits from the aligner AN. Next, the aligner AN aligns the substrate W. Next, the second transfer device TR2 takes out the substrate W from the aligner AN, transports the taken-out substrate W to the load lock chamber LL1, and exits from the load lock chamber LL1. Next, the interior of the load lock chamber LL1 is switched from an atmospheric atmosphere to a vacuum atmosphere. Thereafter, the first transfer device TR1 takes out the substrate W from the load lock chamber LL1 and transports the taken-out substrate W to the processing device PM1.

[0031] Next, the processing device PM1 performs steps S11 to S15 in the method for modifying a silicon oxide film according to the first embodiment.

[0032] Next, the first transfer device TR1 takes out the substrate W from the processing device PM1, transports the taken-out substrate W to the load lock chamber LL3, and exits from the load lock chamber LL3. Subsequently, the interior of the load lock chamber LL3 is switched from a vacuum atmosphere to an atmospheric atmosphere. Thereafter, the second transfer device TR2 takes out the substrate W from the load lock chamber LL3 and accommodates the taken-out substrate W in the carrier C. Then, the processing of the substrate W is completed.

[0033] In the operation of the above-described processing system PS, the case where steps S11 to S15 are performed using one processing device PM1 has been described, but it is not limited thereto. For example, steps S11 to S15 may be performed using at least one of the other processing devices PM2 to PM4. For example, steps S11 to S15 may be performed using two or more of the four processing devices PM1 to PM4. For example, step S11 may be performed using the processing device PM1, and steps S12 to S15 may be performed using the processing device PM2. In this case, the time required for temperature change when performing step S11 and steps S12 to S15 at different temperatures can be shortened. Therefore, productivity is improved.

[0034] (Substrate processing apparatus) With reference to FIG. 5, an example of a substrate processing apparatus used as the processing devices PM1 to PM4 included in the processing system PS of FIG. 4 will be described.

[0035] The substrate processing apparatus includes a processing container 1, a mounting table 2, a shower head 3, an exhaust unit 4, a gas supply unit 5, an RF power supply unit 8, and a control unit 9.

[0036] The processing container 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing container 1 houses a substrate W. The substrate W may be, for example, a semiconductor wafer. An inlet / outlet 11 for loading or unloading the substrate W is formed in the side wall of the processing container 1. The inlet / outlet 11 is opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing container 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 top wall 14 is provided on the upper surface of the exhaust duct 13 so as to close the upper opening of the processing container 1 via an insulating member 16. The space between the exhaust duct 13 and the insulating member 16 is hermetically sealed by a seal member 15. The seal member 15 may be, for example, an O-ring. The partitioning member 17 partitions the inside of the processing container 1 vertically when the mounting table 2 (and the cover member 22) rises to the processing position described later.

[0037] The mounting table 2 horizontally supports the substrate W inside the processing container 1. The mounting table 2 has a disc shape. The outer diameter of the mounting table 2 is larger than, for example, the outer diameter of the substrate W. The mounting table 2 is formed of a ceramic material such as AlN, or a metal material such as aluminum or nickel alloy. Inside the mounting table 2, a heater 21 for heating the substrate W is embedded. The heater 21 is supplied with power from a heater power supply (not shown) and generates heat. Near the upper surface of the mounting table 2, a thermocouple (not shown) is provided. By controlling the output of the heater 21 based on the temperature signal of the thermocouple, the substrate W is controlled to a predetermined temperature. The mounting table 2 is provided with a cover member 22 formed of a ceramic such as alumina so as to cover the outer peripheral region and the side surface of the upper surface.

[0038] A support member 23 is provided on the bottom surface of the mounting table 2. The support member 23 supports the mounting table 2. The support member 23 extends downward from the center of the bottom surface of the mounting table 2 through a hole formed in the bottom wall of the processing container 1 and extends below the processing container 1. The lower end of the support member 23 is connected to an elevating mechanism 24. The elevating mechanism 24 elevates the mounting table 2 via the support member 23 between the processing position shown in FIG. 5 and the transfer position where the substrate W can be transferred shown by the two-dot chain line below it. A flange portion 25 is attached below the processing container 1 of the support member 23. A bellows 26 is provided between the bottom surface of the processing container 1 and the flange portion 25. The bellows 26 partitions the atmosphere inside the processing container 1 from the outside air and expands and contracts as the mounting table 2 moves up and down.

[0039] Near the bottom surface of the processing container 1, three (only two are shown) support pins 27 are provided so as to protrude upward from the elevating plate 27a. The support pins 27 are moved up and down via the elevating plate 27a by an elevating mechanism 28 provided below the processing container 1. The support pins 27 are inserted into through holes 2a provided in the mounting table 2 in the transfer position and can protrude and retract with respect to the upper surface of the mounting table 2. By moving the support pins 27 up and down, the substrate W is transferred between the first transfer device TR1 (FIG. 4) and the mounting table 2.

[0040] The shower head 3 supplies the processing gas in a shower form into the processing vessel 1. The shower head 3 is made of metal and is provided so as to face the mounting table 2. The shower head 3 has substantially the same diameter as the mounting table 2. The shower head 3 has a main body portion 31 and a shower plate 32. The main body portion 31 is fixed to the ceiling wall 14 of the processing vessel 1. The shower plate 32 is connected below the main body portion 31. A gas diffusion space 33 is formed between the main body portion 31 and the shower plate 32. A gas introduction hole 36 is provided in the gas diffusion space 33 so as to penetrate the center of the ceiling wall 14 and the main body portion 31. An annular protrusion 34 protruding downward is formed at the peripheral edge of the shower plate 32. Gas discharge holes 35 are formed in the flat portion inside the annular protrusion 34. In a state where the mounting table 2 exists at the processing position, a processing space 38 is formed between the mounting table 2 and the shower plate 32, and an annular gap 39 is formed by the upper surface of the cover member 22 and the annular protrusion 34 being close to each other.

[0041] The exhaust unit 4 exhausts the inside of the processing vessel 1. The exhaust unit 4 has an exhaust pipe 41 and an exhaust mechanism 42. The exhaust pipe 41 is connected to the exhaust port 13b. The exhaust mechanism 42 has a vacuum pump connected to the exhaust pipe 41 and a pressure control valve. During processing, the gas in the processing vessel 1 reaches the exhaust duct 13 through the slit 13a, and is exhausted by the exhaust mechanism 42 through the exhaust pipe 41 from the exhaust duct 13.

[0042] The gas supply unit 5 supplies various processing gases to the shower head 3. The gas supply unit 5 has a gas source 51 and a gas line 52. The gas source 51 includes a supply source of various processing gases, a mass flow controller, and a valve. The various processing gases include at least the gases used in the method for modifying a silicon oxide film according to the first embodiment. The various gases are introduced from the gas source 51 into the gas diffusion space 33 through the gas line 52 and the gas introduction hole 36.

[0043] The substrate processing apparatus is a capacitively coupled plasma apparatus, in which the mounting table 2 functions as a lower electrode and the shower head 3 functions as an upper electrode. The mounting table 2 is grounded. The shower head 3 is connected to the RF power supply unit 8.

[0044] The RF power supply unit 8 supplies high-frequency power (hereinafter also referred to as "RF power") to the shower head 3. The RF power supply unit 8 includes an RF power source 81, a matcher 82, and a power supply line 83. The RF power source 81 is a power source that generates RF power. The RF power has a frequency suitable for plasma generation. The frequency of the RF power is, for example, a frequency within the range from 450 KHz in the low-frequency band to 2.45 GHz in the microwave band. The RF power source 81 is connected to the main body 31 via the matcher 82 and the power supply line 83. The matcher 82 has a circuit for matching the load impedance to the internal impedance of the RF power source 81. The RF power supply unit 8 may be configured to supply RF power to the mounting table 2.

[0045] The control unit 9 is, for example, a computer. The control unit 9 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device and controls the operation of the substrate processing apparatus. The control unit 9 may be provided inside the substrate processing apparatus or outside it. When the control unit 9 is provided outside the substrate processing apparatus, the control unit 9 can control the substrate processing apparatus by means of communication such as wired or wireless.

[0046] 〔Second Embodiment〕 Referring to FIG. 6, a method for modifying a silicon oxide film according to the second embodiment will be described. The method for modifying a silicon oxide film according to the second embodiment includes steps S21 to S26 shown in FIG. 6. Steps S21 to S24 are the same as steps S11 to S14. Step S26 is the same as step S15.

[0047] Step S25 is executed when the number of executions of steps S22 to S23 reaches the first number in step S24 (YES in step S24). In step S25, it is determined whether steps S21 to S24 have been executed the second number of times. If the number of executions has not reached the second number (NO in step S25), steps S21 to S24 are executed again. On the other hand, if the number of executions has reached the second number (YES in step S25), the process proceeds to step S26. The second number is set according to, for example, the target film thickness of the silicon oxide film 102. The second number may be once or two or more times.

[0048] As described above, according to the method for modifying a silicon oxide film according to the second embodiment, it includes a step of preparing a substrate 100 on which the silicon oxide film 102 is formed, and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S22, step S23, and step S26. In step S22, the surface of the silicon oxide film 102 is exposed to the plasma P1 generated from the first gas containing hydrogen gas. In step S23, the surface of the silicon oxide film 102 is exposed to the plasma P2 generated from the second gas containing argon gas and not containing hydrogen gas. In step S26, the surface of the silicon oxide film 102 is exposed to the plasma P3 generated from the third gas containing nitrogen gas. In this case, similar to the method for modifying a silicon oxide film according to the first embodiment, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0049] The method for modifying a silicon oxide film according to the second embodiment can be implemented using the processing system PS according to the first embodiment, similar to the method for modifying a silicon oxide film according to the first embodiment.

[0050] 〔Third Embodiment〕 Referring to FIG. 7, a method for modifying a silicon oxide film according to the third embodiment will be described. The method for modifying a silicon oxide film according to the third embodiment includes steps S31 to S37 shown in FIG. 7. Steps S31 to S34 are the same as steps S11 to S14. Step S35 is the same as step S25. Step S36 is the same as step S15.

[0051] Step S37 is performed after step S36. In step S37, it is determined whether steps S31 to S36 have been performed for the third number of times. If the number of executions has not reached the third number of times (NO in step S37), steps S31 to S36 are performed again. On the other hand, if the number of executions has reached the third number of times (YES in step S37), the process is terminated. The third number of times is set according to, for example, the target film thickness of the silicon oxide film 102. The third number of times may be once or two or more times.

[0052] As described above, according to the method for modifying a silicon oxide film according to the third embodiment, it includes a step of preparing a substrate 100 on which the silicon oxide film 102 is formed, and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S32, step S33, and step S36. In step S32, the surface of the silicon oxide film 102 is exposed to the plasma P1 generated from the first gas containing hydrogen gas. In step S33, the surface of the silicon oxide film 102 is exposed to the plasma P2 generated from the second gas containing argon gas and not containing hydrogen gas. In step S36, the surface of the silicon oxide film 102 is exposed to the plasma P3 generated from the third gas containing nitrogen gas. In this case, similar to the method for modifying a silicon oxide film according to the first embodiment, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0053] The method for modifying a silicon oxide film according to the third embodiment can be implemented using the processing system PS according to the first embodiment, similar to the method for modifying a silicon oxide film according to the first embodiment.

[0054] 〔Fourth Embodiment〕 Referring to FIG. 8, a method for modifying a silicon oxide film according to the fourth embodiment will be described. The method for modifying a silicon oxide film according to the fourth embodiment includes steps S41 to S45 shown in FIG. 8. The method for modifying a silicon oxide film according to the fourth embodiment is different from the method for modifying a silicon oxide film according to the first embodiment in that the surface of the silicon oxide film 102 is irradiated in the order of plasma P3, plasma P1, and plasma P2.

[0055] Step S41 is the same as step S11. Step S42 is the same as step S15. Steps S43 to S45 are the same as steps S12 to S14.

[0056] As described above, according to the method for modifying a silicon oxide film according to the fourth embodiment, there are a step of preparing a substrate 100 on which the silicon oxide film 102 is formed and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S43, step S44, and step S42. In step S43, the surface of the silicon oxide film 102 is irradiated with plasma P1 generated from a first gas containing hydrogen gas. In step S44, the surface of the silicon oxide film 102 is irradiated with plasma P2 generated from a second gas containing argon gas and not containing hydrogen gas. In step S42, the surface of the silicon oxide film 102 is irradiated with plasma P3 generated from a third gas containing nitrogen gas. In this case, similar to the method for modifying a silicon oxide film according to the first embodiment, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0057] The method for modifying a silicon oxide film according to the fourth embodiment can be implemented using the processing system PS according to the first embodiment, similar to the method for modifying a silicon oxide film according to the first embodiment.

[0058] 〔Fifth Embodiment〕 Referring to FIG. 9, a method for modifying a silicon oxide film according to the fifth embodiment will be described. The method for modifying a silicon oxide film according to the fifth embodiment includes steps S51 to S56 shown in FIG. 9. Steps S51 to S55 are the same as steps S41 to S45.

[0059] Step S56 is performed when the number of executions of steps S53 to S54 in step S55 has reached the first number (YES in step S55). In step S56, it is determined whether steps S52 to S55 have been executed a second number of times. If the number of executions has not reached the second number (NO in step S56), steps S52 to S55 are executed again. On the other hand, if the number of executions has reached the second number (YES in step S56), the process ends. The second number is set according to, for example, the film thickness of the silicon oxide film 102 formed in step S51. The second number may be once or two or more times.

[0060] As described above, according to the method for modifying a silicon oxide film according to the fifth embodiment, it includes a step of preparing a substrate 100 on which the silicon oxide film 102 is formed and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S53, step S54, and step S52. In step S53, the surface of the silicon oxide film 102 is exposed to the plasma P1 generated from the first gas containing hydrogen gas. In step S54, the surface of the silicon oxide film 102 is exposed to the plasma P2 generated from the second gas containing argon gas and not containing hydrogen gas. In step S52, the surface of the silicon oxide film 102 is exposed to the plasma P3 generated from the third gas containing nitrogen gas. In this case, similar to the method for modifying a silicon oxide film according to the first embodiment, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0061] The method for modifying a silicon oxide film according to the fifth embodiment can be implemented using the processing system PS according to the first embodiment, similar to the method for modifying a silicon oxide film according to the first embodiment.

[0062] 〔Embodiment 6〕 Referring to FIG. 10, a method for modifying a silicon oxide film according to the sixth embodiment will be described. The method for modifying a silicon oxide film according to the sixth embodiment includes steps S61 to S67 shown in FIG. 10. Steps S61 to S66 are the same as steps S51 to S56.

[0063] Step S67 is performed when the number of executions of steps S62 to S65 in step S66 has reached the second number (YES in step S66). In step S67, it is determined whether steps S61 to S66 have been executed for the third time. If the number of executions has not reached the third number (NO in step S67), steps S61 to S66 are executed again. On the other hand, if the number of executions has reached the third number (YES in step S67), the process ends. The third number is set according to, for example, the target film thickness of the silicon oxide film 102. The third number may be 1 or may be 2 or more.

[0064] As described above, according to the method for modifying a silicon oxide film according to the sixth embodiment, it includes a step of preparing a substrate 100 on which the silicon oxide film 102 is formed and a step of modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes step S63, step S64, and step S62. In step S63, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S64, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas and not containing hydrogen gas. In step S62, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, similar to the method for modifying a silicon oxide film according to the first embodiment, the leakage current of the silicon oxide film 102 can be reduced. That is, the electrical characteristics of the silicon oxide film 102 can be improved.

[0065] The method for modifying a silicon oxide film according to the sixth embodiment can be implemented using the processing system PS according to the first embodiment, similar to the method for modifying a silicon oxide film according to the first embodiment.

[0066] [Example] (Example 1) In Example 1, the steps of forming a silicon oxide film on a substrate and modifying the silicon oxide film were repeated three times in this order. In the steps of forming the silicon oxide film and modifying the silicon oxide film, the substrate temperature was fixed at 130°C.

[0067] In the step of forming the silicon oxide film, a silicon oxide film was formed on the substrate by supplying TMA gas to the substrate and then supplying TPSOL gas. TMA gas is an example of a metal catalyst gas. TPSOL gas is an example of a silanol-containing gas.

[0068] In the step of modifying the silicon oxide film, first, a process of exposing the surface of the silicon oxide film to the plasma generated from hydrogen gas and argon gas and a process of exposing the surface of the silicon oxide film to the plasma generated from argon gas were repeated three times in this order. Then, a process of exposing the surface of the silicon oxide film to the plasma generated from nitrogen gas, argon gas, and hydrogen gas was performed. Hereinafter, the process of repeating the step of exposing the surface of the silicon oxide film to the plasma generated from hydrogen gas and argon gas and the step of exposing the surface of the silicon oxide film to the plasma generated from argon gas in this order is also referred to as cyclic plasma treatment. The process of exposing the surface of the silicon oxide film to the plasma generated from nitrogen gas, argon gas, and hydrogen gas is also referred to as nitrogen plasma treatment.

[0069] In the nitrogen plasma treatment, the time per cycle was fixed at 15 seconds. In the nitrogen plasma treatment, while fixing the flow rate of argon gas at 3000 sccm and the total flow rate of nitrogen gas and hydrogen gas at 2000 sccm, the flow rate ratio of nitrogen gas and hydrogen gas was changed by changing the flow rate of nitrogen gas and the flow rate of hydrogen gas.

[0070] Next, the film thickness and leakage current density of the silicon oxide film formed on the substrate were measured. A spectroscopic ellipsometer was used to measure the film thickness. The leakage current density was measured using a mercury probe. The leakage current density was defined as the current density flowing through the silicon oxide film when an electric field of 5 MV / cm and 3 MV / cm was applied to the silicon oxide film. The electric field was obtained by dividing the applied voltage by the film thickness. The current density was obtained by dividing the measured current at the time of voltage application by the electrode area of the mercury probe.

[0071] Figures 11 and 12 are diagrams showing the leakage current density of the silicon oxide film. Figure 11 shows the leakage current density when an electric field of 5 MV / cm is applied to the silicon oxide film. Figure 12 shows the leakage current density when an electric field of 3 MV / cm is applied to the silicon oxide film. In Figures 11 and 12, the horizontal axis indicates the flow rate of nitrogen gas [sccm], and the vertical axis indicates the leakage current density of the silicon oxide film [A / cm 2 .

[0072] As shown in Figure 11, the leakage current densities of the silicon oxide film when the flow rate of nitrogen gas in the nitrogen plasma treatment is 0 sccm, 250 sccm, 500 sccm, 1000 sccm, 1500 sccm, and 2000 sccm are 1.1×10 -7 A / cm 2 , 2.8×10 -8 A / cm 2 , 2.4×10 -8 A / cm 2 , 3.0×10 -8 A / cm 2 , 4.5×10 -8 A / cm 2 , and 2.0×10 -8 A / cm 2 , respectively.

[0073] When the flow rate of nitrogen gas in the nitrogen plasma treatment is in the range of 250 sccm to 2000 sccm, the leakage current density of the silicon oxide film is smaller than that when the flow rate of nitrogen gas in the nitrogen plasma treatment is 0 sccm. From this result, it can be said that by performing nitrogen plasma treatment after cyclic plasma treatment, the leakage current of the silicon oxide film can be reduced.

[0074] When the flow rate of nitrogen gas in nitrogen plasma treatment is 250 sccm to 2000 sccm, there is no significant difference in the leakage current density of the silicon oxide film. From this result, it can be said that the leakage current of the silicon oxide film can be reduced regardless of the flow rate of nitrogen gas in nitrogen plasma treatment.

[0075] As shown in FIG. 12, the leakage current densities of the silicon oxide film when the flow rate of nitrogen gas in nitrogen plasma treatment is 0 sccm, 250 sccm, 500 sccm, 1000 sccm, 1500 sccm, and 2000 sccm are 2.3×10 -8 A / cm 2 、1.3×10 -8 A / cm 2 、1.0×10 -8 A / cm 2 、1.1×10 -8 A / cm 2 、1.8×10 -8 A / cm 2 、and 3.6×10 -9 A / cm 2 respectively.

[0076] When the flow rate of nitrogen gas in nitrogen plasma treatment is 2000 sccm, the leakage current density of the silicon film is smaller than that when the flow rate of nitrogen gas in nitrogen plasma treatment is 250 sccm, 500 sccm, 1000 sccm, and 1500 sccm. From this result, it can be said that in nitrogen plasma treatment, the leakage current of the silicon oxide film can be reduced more when hydrogen gas is not included than when hydrogen gas is included.

[0077] (Example 2) In Example 2, the step of forming a silicon oxide film on the substrate and the step of modifying the silicon oxide film were repeated three times in this order. In the step of forming a silicon oxide film and the step of modifying the silicon oxide film, the substrate temperature was fixed at 130°C. The step of forming a silicon oxide film is the same as in Example 1.

[0078] In the step of modifying the silicon oxide film, the silicon oxide film was modified under the conditions 2A to 2E shown below.

[0079] <Condition 2A> After performing cyclic plasma treatment, nitrogen plasma treatment was performed.

[0080] <Condition 2B> After performing nitrogen plasma treatment, cyclic plasma treatment was performed.

[0081] <Condition 2C> Only cyclic plasma treatment was performed without performing nitrogen plasma treatment.

[0082] <Condition 2D> Only nitrogen plasma treatment was performed without performing cyclic plasma treatment.

[0083] <Condition 2E> Neither cyclic plasma treatment nor nitrogen plasma treatment was performed.

[0084] In conditions 2A to 2E, in all cases, the flow rate of nitrogen gas in the nitrogen plasma treatment was set to 250 sccm, the flow rate of hydrogen gas was set to 1750 sccm, and the flow rate of argon gas was set to 3000 sccm.

[0085] Next, the film thickness and leakage current density of the silicon oxide film formed on the substrate were measured. For the measurement of the film thickness, a spectroscopic ellipsometer was used. The leakage current density was measured using a mercury probe. The leakage current density was defined as the current density flowing through the silicon oxide film when an electric field of 5 MV / cm was applied to the silicon oxide film. The electric field was obtained by dividing the applied voltage by the film thickness. The current density was obtained by dividing the measured current at the time of voltage application by the electrode area of the mercury probe.

[0086] Figure 13 is a diagram showing the leakage current density of the silicon oxide film. Figure 13 shows the leakage current density of the silicon oxide film when the conditions for modifying the silicon oxide film are changed. In Figure 13, the leakage current density of the silicon oxide film when the silicon oxide film is modified under conditions 2A, 2B, 2C, 2D, and 2E in order from the left is shown in [A / cm 2 .

[0087] As shown in Figure 13, the leakage current densities of the silicon oxide film when the silicon oxide film is modified under conditions 2A, 2B, 2C, 2D, and 2E are 2.8×10 -8 A / cm 2 , 3.3×10 -8 A / cm 2 , 6.4×10 -7 A / cm 2 , 6.9×10 -6 A / cm 2 , and 7.3×10 -6 A / cm 2 , respectively.

[0088] For conditions 2A and 2B, the leakage current density of the silicon oxide film is significantly lower compared to condition 2E, while for conditions 2C and 2D, the reduction in the leakage current density of the silicon oxide film is smaller compared to condition 2E. From this result, it can be said that by performing cyclic plasma treatment and nitrogen plasma treatment on the silicon oxide film, the leakage current of the silicon oxide film can be reduced compared to the case where only either cyclic plasma treatment or nitrogen plasma treatment is performed on the silicon oxide film.

[0089] There is almost no difference in the leakage current density of the silicon oxide film between conditions 2A and 2B. From this result, it can be said that even when the nitrogen plasma treatment is performed before the cyclic plasma treatment, the leakage current of the silicon oxide film can be reduced to the same extent as when the nitrogen plasma treatment is performed after the cyclic plasma treatment.

[0090] The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The above embodiments may be omitted, replaced, or changed in various forms without departing from the scope and spirit of the appended claims.

[0091] In the above embodiment, the case of forming a silicon oxide film using a metal catalyst gas and a silanol-containing gas has been described, but the present disclosure is not limited thereto. For example, a silicon oxide film may be formed using a silicon-containing gas and an oxidizing agent.

[0092] In the above embodiment, the case where the hydrogen-containing gas is hydrogen gas, the nitrogen-containing gas is nitrogen gas, and the inert gas is argon gas has been described, but the present disclosure is not limited thereto. The nitrogen-containing gas may be ammonia gas. The inert gas may be a noble gas other than argon gas, for example, helium gas.

Description of Reference Numerals

[0093] 100 Substrate 102 Silicon Oxide Film P1, P2, P3 Plasma

Claims

1. A step of preparing a substrate with a silicon oxide film formed thereon, A step of modifying the silicon oxide film, characterized by comprising: The step of modifying the silicon oxide film includes: (a) A step of exposing the surface of the silicon oxide film to plasma generated from a first gas containing a hydrogen-containing gas; (b) A step of exposing the surface of the silicon oxide film to plasma generated from a second gas containing an inert gas and not containing a hydrogen-containing gas; (c) A step of exposing the surface of the silicon oxide film to plasma generated from a third gas containing a nitrogen-containing gas; A method for modifying a silicon oxide film.

2. The steps (a), (b), and (c) are performed in this order, The method for modifying a silicon oxide film according to Claim 1.

3. The step of modifying the silicon oxide film includes (d) a step of repeating the steps (a) and (b), The method for modifying a silicon oxide film according to Claim 1.

4. The step of modifying the silicon oxide film includes (e) a step of repeating the steps (a), (b), and (c), The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

5. Maintaining the plasma when switching between the steps (a) and (b), The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

6. Stopping the plasma when switching between the steps (a) and (b), The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

7. Maintaining the plasma when switching between the steps (b) and (c), The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

8. Stopping the plasma when switching between the steps (b) and (c), The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

9. The first gas contains the inert gas, The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

10. Maintaining the supply of the inert gas when switching between the steps (a) and (b), The method for modifying a silicon oxide film according to Claim 9.

11. The third gas contains the inert gas, The method for modifying a silicon oxide film according to any one of Claims 1 to 3.

12. The third gas contains the hydrogen-containing gas, The method for modifying a silicon oxide film according to Claim 11. ​

13. The third gas does not contain the hydrogen-containing gas, A method for modifying a silicon oxide film according to claim 11.

14. The ratio of the flow rate of the nitrogen-containing gas contained in the third gas is 5% or more and 40% or less, A method for modifying a silicon oxide film according to claim 12.

15. The hydrogen-containing gas is hydrogen gas, The inert gas is argon gas, The nitrogen-containing gas is nitrogen gas, A method for modifying a silicon oxide film according to any one of claims 1 to 3.

16. The step of preparing includes A step of supplying a metal catalyst gas to the substrate and adsorbing the metal catalyst gas on the surface of the substrate, A step of supplying a silanol-containing gas to the substrate and reacting the silanol-containing gas with the metal catalyst gas adsorbed on the surface to form the silicon oxide film, including, A method for modifying a silicon oxide film according to any one of claims 1 to 3.

17. The step of preparing includes a step of repeating the step of adsorbing the metal catalyst gas and the step of forming the silicon oxide film, A method for modifying a silicon oxide film according to claim 16.

18. A method for modifying a silicon oxide film according to claim 17, which has a step of repeating the step of adsorbing the metal catalyst gas, the step of forming the silicon oxide film, and the step of modifying the silicon oxide film. A method for modifying a silicon oxide film according to claim 17.

19. The step of modifying the silicon oxide film is performed at a temperature higher than the step of adsorbing the metal catalyst gas and the step of forming the silicon oxide film, A method for modifying a silicon oxide film according to claim 16.

20. A processing container, A gas supply unit for supplying gas into the processing container, A control unit, comprising, The control unit A step of preparing a substrate on which a silicon oxide film is formed, A step of modifying the silicon oxide film, is configured to control the gas supply unit so as to perform, The step of modifying the silicon oxide film (a) A step of exposing the surface of the silicon oxide film to plasma generated from a first gas containing a hydrogen-containing gas, (b) A step of exposing the surface of the silicon oxide film to plasma generated from a second gas containing an inert gas and not containing a hydrogen-containing gas, (c) A step of exposing the surface of the silicon oxide film to plasma generated from a third gas containing a nitrogen-containing gas, including, A substrate processing apparatus.

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