Silicon oxide film modification method and substrate processing device

Abstract

A silicon oxide film modification method according to one aspect of the present disclosure comprises: a step for preparing a substrate on which a silicon oxide film has been formed; and a step for modifying the silicon oxide film. The step for modifying the silicon oxide film includes (a) a step for exposing a surface of the silicon oxide film to plasma that has been generated from a first gas including a hydrogen-containing gas, (b) a step for exposing the surface of the silicon oxide film to plasma that has been generated from a second gas not including a hydrogen-containing gas but including an inert gas, and (c) a step for exposing the surface of the silicon oxide film to plasma that has been generated from a third gas including a nitrogen-containing gas.

Description

Silicon oxide film modification method and substrate processing apparatus

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

[0002] A technique for modifying a silicon oxide film by exposing a substrate on which the silicon oxide film has been formed to plasma generated from a mixed gas of hydrogen gas and argon gas and plasma generated from argon gas is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-182324

[0004] The present disclosure provides a technique that can improve the electrical properties of a silicon oxide film.

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

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

[0007] FIG. 1 is a flowchart showing a method for modifying a silicon oxide film according to a first embodiment. FIG. 2 is a cross-sectional view showing a method for modifying a silicon oxide film according to a first embodiment. FIG. 3 is a cross-sectional view showing a method for modifying a silicon oxide film according to a first embodiment. FIG. 4 is a cross-sectional view showing a method for modifying a silicon oxide film according to a first embodiment. FIG. 5 is a cross-sectional view showing a method for modifying a silicon oxide film according to a first embodiment. FIG. 6 is a flowchart showing an example of steps for forming a silicon oxide film. FIG. 7 is a diagram showing an example of a processing system according to an embodiment. FIG. 8 is a diagram showing an example of a substrate processing apparatus according to an embodiment. FIG. 9 is a flowchart showing a method for modifying a silicon oxide film according to a second embodiment. FIG. 10 is a flowchart showing a method for modifying a silicon oxide film according to a third embodiment. FIG. 11 is a flowchart showing a method for modifying a silicon oxide film according to a fourth embodiment. FIG. 12 is a flowchart showing a method for modifying a silicon oxide film according to a fifth embodiment. FIG. 13 is a flowchart showing a method for modifying a silicon oxide film according to a sixth embodiment. FIG. 14 is a diagram showing the leakage current density of a silicon oxide film.

[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 reference numerals are used to designate the same or corresponding members or components, and redundant descriptions will be omitted.

[0009] [First Embodiment] (Method for Modifying Silicon Oxide Film) A method for modifying a silicon oxide film according to a first embodiment will be described with reference to Figures 1 to 3. The method for modifying a silicon oxide film according to the first embodiment includes steps S11 to S15 shown in Figure 1.

[0010] In step S11, as shown in FIG. 2A, 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-k film. The type of insulating film 101 is not particularly limited, but may be, for example, a SiO film, a SiN film, a SiOC film, a SiON film, or a SiOCN film. An SiO film refers to a film containing silicon (Si) and oxygen (O). The atomic ratio of Si to O in a SiO film is not limited to 1:1. The same applies to SiN films, SiOC films, SiON films, and SiOCN films. 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 adsorbed onto the insulating film 101. The metal catalyst gas is, for example, trimethylaluminum (TMA) gas. In step S111, the substrate 100 is heated to a low temperature, for example, at a temperature of 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 the silicon oxide film 102. The silanol-containing gas is, for example, TPSOL (Tris(tert-pentoxy)silanol) or TBSOL (Tris(tert-butoxy)silanol). In step S112, the substrate 100 is heated to a low temperature, for example, at a temperature of 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 a set number of times. If the number of times has not reached the set number (NO in step S113), steps S111 to S112 are performed again. If the number of times has reached the set number of times (YES in step S113), the thickness of the silicon oxide film 102 has reached the predetermined thickness for the plasma processing, and the processing is terminated. The set number of times in step S113 is set according to the film formation amount so that the silicon oxide film 102 formed in step S11 achieves the predetermined thickness. The film formation amount can be adjusted by, for example, the supply amount of silanol-containing gas. The predetermined film thickness is, for example, 2 nm to 5 nm. In this case, in steps S12 to S15, the plasma is likely to act on the entire thickness direction of the silicon oxide film 102 formed in the immediately preceding step S11. As a result, the silicon oxide film 102 is modified throughout the entire thickness direction. On the other hand, if the thickness of the silicon oxide film 102 formed in step S11 is larger than the predetermined thickness, it is difficult for the plasma to modify the silicon oxide film 102 at a deep position from the surface in steps S12 to S15. The number of times step S113 is performed may be one, two or more.

[0014] Step S12 is performed after step S11. In step S12, as shown in FIG. 2B , the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. This removes impurities in the film, including Si—OH bonds. In step S12, when the silicon oxide film 102 is exposed to plasma P1, active species contained in the plasma P1 react with the silicon oxide film 102, which can generate hydrogen defects in the silicon oxide film 102. The first gas may be mixed with argon gas. In step S12, the substrate 100 may be heated to a temperature higher than that in step S11. In this case, impurities in the film, including Si—OH bonds, are more likely to be removed.

[0015] An example of the processing conditions for step S12 is as follows: Hydrogen gas flow rate: 200 sccm to 3000 sccm Argon gas flow rate: 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. 2C, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas but not hydrogen gas. This removes hydrogen defects generated in the silicon oxide film 102 in step S12. As a result, both impurities in the film, such as Si—OH bonds, and hydrogen defects can be reduced. This makes it easier to reduce leakage current in the silicon oxide film 102 than in modification using only plasma P1 or only plasma P2. In step S13, the substrate 100 may be heated to a temperature higher than that in step S11. In this case, hydrogen defects are more easily removed. When transitioning from step S12 to step S13, plasma P2 may be generated while plasma P1 is maintained, or plasma P2 may be generated after plasma P1 is stopped.

[0017] An example of the processing conditions for step S13 is as follows: Argon gas flow rate: 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 a first number of times. If the number of times has not reached the first number (NO in step S14), steps S12 to S13 are performed again. On the other hand, if the number of times has reached the first number of times (YES in step S14), the process proceeds to step S15. The first number of times is set, for example, according to the film thickness of the silicon oxide film 102 formed in step S11. The first number of times may be one time, or may be two or more times. The first number of times is preferably two to six times. When transitioning from step S13 to step S12, the plasma P2 may be maintained while being switched to plasma P1, or plasma P1 may be generated after plasma P2 is stopped.

[0019] In step S15, as shown in FIG. 2D , the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. This further reduces the leakage current of the silicon oxide film 102. This is believed to be because the exposure of the silicon oxide film 102 to plasma P3 inactivates electrically active defects present on the surface and inside of the silicon oxide film 102. The third gas may contain argon gas. The third gas may also contain hydrogen gas. The flow rate of 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, leakage current is more likely to be reduced. When transitioning from step S13 to step S15, plasma P3 may be generated while maintaining plasma P2, or plasma P3 may be generated after plasma P2 is stopped.

[0020] An example of the processing conditions for step S15 is as follows: Nitrogen gas flow rate: 200 sccm to 2000 sccm Argon gas flow rate: 600 sccm to 6000 sccm Hydrogen gas flow rate: 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, the method for modifying a silicon oxide film according to the first embodiment includes the steps of preparing a substrate 100 on which a silicon oxide film 102 is formed and modifying the silicon oxide film 102. The step of modifying the silicon oxide film 102 includes steps S12, S13, and 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 but not 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) With reference to FIG. 4, an example of a processing system PS for carrying out the silicon oxide film modifying method according to the first embodiment will be described.

[0023] The processing system PS includes processing devices 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 a general control unit CU.

[0024] The processing devices PM1 to PM4 are connected to the vacuum transfer chamber VTM via gate valves G11 to G14, respectively. The processing devices PM1 to PM4 are configured so that the interior thereof can be depressurized to a predetermined vacuum atmosphere. The processing devices PM1 to PM4 accommodate substrates W therein and perform desired processing.

[0025] The vacuum transfer chamber VTM is configured so that its interior can be depressurized to a predetermined vacuum atmosphere. The vacuum transfer chamber VTM is provided with a first transfer device TR1 capable of transferring substrates W in a depressurized state. The first transfer device TR1 transfers substrates 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 independently movable transfer arms FK11 and FK12.

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

[0027] The atmospheric transfer chamber LM has an atmospheric atmosphere inside. For example, a downflow of clean air is formed inside the atmospheric transfer chamber LM. An aligner AN that aligns the substrate W is provided inside the atmospheric transfer chamber LM. 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 surfaces of the atmospheric transfer chamber LM. Carriers C are attached to the load ports LP1 to LP3. The carriers C include carriers C that house substrates W and empty carriers C. The carriers C may be, for example, front-opening unified pods (FOUPs).

[0029] The overall control unit CU may be, for example, a computer. The overall control unit CU includes a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and an auxiliary storage device. The CPU operates based on a program stored in the ROM or the auxiliary storage device and controls each component of the processing system PS. For example, the overall control unit CU controls the operation 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, and G31 to G33. For example, the overall control unit CU controls the operation of switching the interior of the load lock chambers LL1 to LL3 between the air atmosphere and a vacuum atmosphere.

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

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

[0032] Next, the first transport device TR1 removes the substrate W from the processing device PM1, transports the removed substrate W to the load lock chamber LL3, and exits from the load lock chamber LL3. The interior of the load lock chamber LL3 is then switched from a vacuum atmosphere to an atmospheric atmosphere. Thereafter, the second transport device TR2 removes the substrate W from the load lock chamber LL3 and stores the removed substrate W in the carrier C. Then, the processing of the substrate W is completed.

[0033] In the above-described operation of the processing system PS, steps S11 to S15 are performed using one processing device PM1, but this is not limiting. 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 processing device PM1, and steps S12 to S15 may be performed using processing device PM2. In this case, the time required to change temperatures when performing step S11 and steps S12 to S15 at different temperatures can be reduced. This improves productivity.

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

[0035] The substrate processing apparatus includes a processing chamber 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 vessel 1 is made of a metal such as aluminum and has a substantially cylindrical shape. The processing vessel 1 accommodates a substrate W. The substrate W may be, for example, a semiconductor wafer. A loading / unloading port 11 is formed in a sidewall of the processing vessel 1 for loading and unloading the substrate W. The loading / unloading port 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 vessel 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed in the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 to close the upper opening of the processing vessel 1 via an insulating member 16. A sealing member 15 hermetically seals the space between the exhaust duct 13 and the insulating member 16. The sealing member 15 may be, for example, an O-ring. The partition member 17 partitions the interior of the processing vessel 1 into upper and lower sections when the mounting table 2 (and the cover member 22) is raised to a processing position described below.

[0037] The mounting table 2 horizontally supports the substrate W within the processing chamber 1. The mounting table 2 has a disk shape. The outer diameter of the mounting table 2 is, for example, larger than the outer diameter of the substrate W. The mounting table 2 is made of a ceramic material such as AlN or a metal material such as aluminum or a nickel alloy. A heater 21 for heating the substrate W is embedded inside the mounting table 2. The heater 21 generates heat when power is supplied from a heater power supply (not shown). A thermocouple (not shown) is provided near the top surface of the mounting table 2. The output of the heater 21 is controlled by a temperature signal from the thermocouple, thereby controlling the substrate W to a predetermined temperature. A cover member 22 made of ceramic such as alumina is provided on the mounting table 2 to cover the outer peripheral region of the top surface and the side surfaces.

[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 from the center of the bottom surface of the mounting table 2 to below the processing vessel 1, passing through a hole formed in the bottom wall of the processing vessel 1. The lower end of the support member 23 is connected to a lifting mechanism 24. The lifting mechanism 24 raises and lowers the mounting table 2, via the support member 23, between a processing position shown in FIG. 5 and a transfer position, shown by a two-dot chain line below, where a substrate W can be transferred. A flange 25 is attached to the support member 23 below the processing vessel 1. A bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25. The bellows 26 separates the atmosphere inside the processing vessel 1 from the outside air and expands and contracts as the mounting table 2 is raised and lowered.

[0039] Three support pins 27 (only two are shown) are provided near the bottom surface of the processing vessel 1 so as to protrude upward from a lifting plate 27a. The support pins 27 are raised and lowered via the lifting plate 27a by a lifting mechanism 28 provided below the processing vessel 1. The support pins 27 are inserted into through holes 2a provided in the mounting table 2 at the transport position, and are capable of protruding and retracting from the upper surface of the mounting table 2. By raising and lowering the support pins 27, the substrate W is transferred between the first transport device TR1 ( FIG. 4 ) and the mounting table 2.

[0040] The shower head 3 supplies a processing gas into the processing chamber 1 in a shower-like manner. The shower head 3 is made of metal and is disposed opposite the mounting table 2. The shower head 3 has approximately the same diameter as the mounting table 2. The shower head 3 includes a main body 31 and a shower plate 32. The main body 31 is fixed to the ceiling wall 14 of the processing chamber 1. The shower plate 32 is connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32. A gas inlet hole 36 is formed in the gas diffusion space 33 so as to penetrate the center of the ceiling wall 14 and the main body 31. A downwardly protruding annular protrusion 34 is formed on the periphery of the shower plate 32. A gas outlet hole 35 is formed in the inner flat portion of the annular protrusion 34. When the mounting table 2 is in the processing position, a processing space 38 is formed between the mounting table 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion 34 are close to each other to form an annular gap 39.

[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, gas inside the processing vessel 1 reaches the exhaust duct 13 through the slit 13a, passes from the exhaust duct 13 through the exhaust pipe 41, and is exhausted by the exhaust mechanism 42.

[0042] The gas supply unit 5 supplies various process 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 supply sources of various process gases, a mass flow controller, and a valve. The various process gases include at least the gases used in the silicon oxide film modification method according to the first embodiment. The various gases are introduced from the gas source 51 into the gas diffusion space 33 via 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 an RF power supply unit 8.

[0044] The RF power supply unit 8 supplies radio frequency power (hereinafter also referred to as "RF power") to the showerhead 3. The RF power supply unit 8 includes an RF power source 81, a matching box 82, and a feed line 83. The RF power source 81 is a power source that generates RF power. The RF power has a frequency suitable for generating plasma. The frequency of the RF power is, for example, within a 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 matching box 82 and the feed line 83. The matching box 82 includes 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), RAM (Random Access Memory), 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 or outside the substrate processing apparatus. When the control unit 9 is provided outside the substrate processing apparatus, the control unit 9 can control the substrate processing apparatus via a communication means such as a wired or wireless communication means.

[0046] Second Embodiment A method for modifying a silicon oxide film according to a second embodiment will be described with reference to Fig. 6. 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 performed when, in step S24, the number of times steps S22 to S23 have been performed reaches the first number (YES in step S24). In step S25, it is determined whether steps S21 to S24 have been performed a second number of times. If the number of times has not reached the second number of times (NO in step S25), steps S21 to S24 are performed again. On the other hand, if the number of times has reached the second number of times (YES in step S25), the process proceeds to step S26. The second number of times is set, for example, according to the target film thickness of the silicon oxide film 102. The second number of times may be one time, or may be two or more times.

[0048] As described above, the silicon oxide film modifying method according to the second embodiment includes 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 steps S22, S23, and S26. In step S22, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S23, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas but not hydrogen gas. In step S26, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, as with the silicon oxide film modifying method 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 silicon oxide film modifying method according to the second embodiment can be carried out using the processing system PS according to the first embodiment, similarly to the silicon oxide film modifying method according to the first embodiment.

[0050] Third Embodiment A method for modifying a silicon oxide film according to a third embodiment will be described with reference to Fig. 7. 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 a third number of times. If the number of times 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 times has reached the third number of times (YES in step S37), the process ends. 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 one time, or may be two or more times.

[0052] As described above, the silicon oxide film modifying method according to the third embodiment includes 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 steps S32, S33, and S36. In step S32, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S33, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas but not hydrogen gas. In step S36, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, as with the silicon oxide film modifying method 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 silicon oxide film modifying method according to the third embodiment can be carried out using the processing system PS according to the first embodiment, similarly to the silicon oxide film modifying method according to the first embodiment.

[0054] Fourth Embodiment A method for modifying a silicon oxide film according to a fourth embodiment will be described with reference to Fig. 8. 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 differs 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 exposed to plasma P3, plasma P1, and plasma P2 in this order.

[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, the silicon oxide film modifying method according to the fourth embodiment includes 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 steps S43, S44, and S42. In step S43, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S44, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas but not hydrogen gas. In step S42, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, as with the silicon oxide film modifying method 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 silicon oxide film modifying method according to the fourth embodiment can be carried out using the processing system PS according to the first embodiment, similarly to the silicon oxide film modifying method according to the first embodiment.

[0058] Fifth Embodiment A method for modifying a silicon oxide film according to a fifth embodiment will be described with reference to Fig. 9. 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, in step S55, steps S53 to S54 have been performed a first number of times (YES in step S55). In step S56, it is determined whether steps S52 to S55 have been performed a second number of times. If the number of times has not reached the second number of times (NO in step S56), steps S52 to S55 are performed again. On the other hand, if the number of times has reached the second number of times (YES in step S56), the process ends. The second number of times is set, for example, depending on the film thickness of the silicon oxide film 102 formed in step S51. The second number of times may be one, two, or more.

[0060] As described above, the silicon oxide film modifying method according to the fifth embodiment includes 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 steps S53, S54, and S52. In step S53, the surface of the silicon oxide film 102 is exposed to plasma P1 generated from a first gas containing hydrogen gas. In step S54, the surface of the silicon oxide film 102 is exposed to plasma P2 generated from a second gas containing argon gas but not hydrogen gas. In step S52, the surface of the silicon oxide film 102 is exposed to plasma P3 generated from a third gas containing nitrogen gas. In this case, as with the silicon oxide film modifying method 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 silicon oxide film modifying method according to the fifth embodiment can be carried out using the processing system PS according to the first embodiment, similarly to the silicon oxide film modifying method according to the first embodiment.

[0062] Sixth Embodiment A method for modifying a silicon oxide film according to a sixth embodiment will be described with reference to Fig. 10. 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, in step S66, steps S62 to S65 have been performed a second number of times (YES in step S66). In step S67, it is determined whether steps S61 to S66 have been performed a third number of times. If the number of times has not reached the third number of times (NO in step S67), steps S61 to S66 are performed again. On the other hand, if the number of times has reached the third number of times (YES in step S67), the process ends. The third number of times is set, for example, according to the target film thickness of the silicon oxide film 102. The third number of times may be one time, or may be two or more times.

[0064] As described above, the silicon oxide film modifying method according to the sixth embodiment includes 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 steps S63, S64, and 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 but not 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, as with the silicon oxide film modifying method 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 silicon oxide film modifying method according to the sixth embodiment can be carried out using the processing system PS according to the first embodiment, similarly to the silicon oxide film modifying method according to the first embodiment.

[0066] 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 silicon oxide film forming process, TMA gas was supplied to the substrate, and then TPSOL gas was supplied to form the silicon oxide film on the substrate. TMA gas is an example of a metal catalyst gas. TPSOL gas is an example of a silanol-containing gas.

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

[0069] The nitrogen plasma treatment was performed for a fixed time of 15 seconds. In the nitrogen plasma treatment, the flow rate of the argon gas was fixed at 3000 sccm, and the total flow rate of the nitrogen gas and the hydrogen gas was fixed at 2000 sccm. The flow rates of the nitrogen gas and the hydrogen gas were changed to change the flow rate ratio of the nitrogen gas to the 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. A mercury probe was used to measure the leakage current density. The leakage current density was determined as the current density flowing through the silicon oxide film when electric fields of 5 MV / cm and 3 MV / cm were applied to the silicon oxide film. The electric field was calculated by dividing the applied voltage by the film thickness. The current density was calculated by dividing the measured current when a voltage was applied by the electrode area of ​​the mercury probe.

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

[0072] As shown in FIG. 11, 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, the leakage current density of the silicon oxide film is 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 It was.

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

[0074] When the nitrogen gas flow rate in the nitrogen plasma treatment is between 250 sccm and 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 nitrogen gas flow rate in the nitrogen plasma treatment.

[0075] As shown in FIG. 12, 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, the leakage current density of the silicon oxide film is 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 It was.

[0076] When the nitrogen gas flow rate in the nitrogen plasma treatment is 2000 sccm, the leakage current density of the silicon film is smaller than when the nitrogen gas flow rate in the nitrogen plasma treatment is 250 sccm, 500 sccm, 1000 sccm, and 1500 sccm. From this result, it can be said that the nitrogen plasma treatment without hydrogen gas can reduce the leakage current of the silicon oxide film more than the nitrogen plasma treatment with hydrogen gas.

[0077] In Example 2, the step of forming a silicon oxide film on a substrate and the step of 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. The step of forming the silicon oxide film was the same as in Example 1.

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

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

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

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

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

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

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

[0085] 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. A mercury probe was used to measure the leakage current density. The leakage current density was determined 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 calculated by dividing the applied voltage by the film thickness. The current density was calculated by dividing the measured current when a voltage was applied by the electrode area of ​​the mercury probe.

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

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

[0088] Conditions 2A and 2B significantly reduce the leakage current density of the silicon oxide film compared to condition 2E, whereas conditions 2C and 2D reduce the leakage current density of the silicon oxide film less than 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 when 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 Condition 2 A and Condition 2 B. 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 herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0091] In the above embodiment, a silicon oxide film is formed using a metal catalyst gas and a silanol-containing gas, 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 hydrogen-containing gas is hydrogen gas, the nitrogen-containing gas is nitrogen gas, and the inert gas is argon gas. However, the present disclosure is not limited to this. The nitrogen-containing gas may be ammonia gas. The inert gas may be a rare gas other than argon gas, such as helium gas.

[0093] This international application claims priority based on Japanese Patent Application No. 2024-005793, filed on January 18, 2024, the entire contents of which are incorporated herein by reference.

[0094] 100: Substrate 102: Silicon oxide film P1, P2, P3: Plasma

Claims

1. A method for modifying a silicon oxide film, comprising: preparing a substrate having a silicon oxide film formed thereon; and modifying the silicon oxide film, wherein the step of modifying the silicon oxide film includes: (a) exposing the surface of the silicon oxide film to plasma generated from a first gas containing a hydrogen-containing gas; (b) 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) exposing the surface of the silicon oxide film to plasma generated from a third gas containing a nitrogen-containing gas.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

16. The step of preparing includes: supplying a metal catalyst gas to the substrate and adsorbing the metal catalyst gas on the surface of the substrate; and 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. The method for modifying a silicon oxide film according to any one of claims 1 to 3.

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

18. The 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.

19. The method for modifying a silicon oxide film according to claim 16, wherein 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.

20. A substrate processing apparatus comprising a processing container, a gas supply unit configured to supply a gas into the processing container, and a control unit, wherein the control unit is configured to control the gas supply unit to perform 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.

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