JP5374748B2 - Insulating film forming method, computer-readable storage medium, and processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an insulating film which planarizes the shape of interface of silicon and an insulating film extremely when the insulating film is formed by CVD. <P>SOLUTION: By using a plasma processing device 100 for introducing a microwave into a chamber 1 by a flat antenna 31 having a plurality of holes, the surface of silicon is oxidized to form a silicon oxide film (step S1) and then a silicon oxide film is deposited thereon as an insulating film by CVD (step S4). Furthermore, by using the plasma processing device 100, processing gas containing rare gas and oxygen is introduced into the chamber 1 and a microwave is introduced by the flat antenna 31, plasma is generated under pressure conditions in the range of 6.7-267 Pa and the insulating film is modified by the plasma (step S6). <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an insulating film forming method for forming an insulating film by a CVD (Chemical Vapor Deposition) method, a computer-readable storage medium, and a processing system.

  The CVD method is widely used for the purpose of forming an insulating film such as a silicon oxide film or a high dielectric constant insulating film in the manufacturing process of various semiconductor devices. In the CVD method, a gas phase reaction is caused in a film forming raw material using energy such as heat to form an insulating film on a target object.

  When the insulating film is formed by the CVD method, the following problems are pointed out. First, the first problem is that the interface state density increases because minute irregularities are formed at the interface between the insulating film and the base film deposited by the CVD method. When the interface state density increases, there is a concern that the mobility of carriers moving at the interface between the base film (for example, a silicon substrate) and the insulating film is lowered, and the electrical performance of the device is lowered.

  In addition, as a second problem, many dangling bonds exist in an insulating film (for example, a silicon oxide film) formed by a CVD method, and impurities such as moisture and chlorine derived from film forming materials However, the film quality is not so good. Therefore, it is necessary to improve the film quality by annealing the insulating film formed by the CVD method at a high temperature of, for example, 700 ° C. or higher. However, since it is impossible to recombine Si—O bonds by heat energy supply, it is difficult to improve the basic film quality by annealing after film formation. Further, in order to enhance the modification effect by the annealing treatment, a treatment at a high temperature is required, but the annealing at a high temperature leads to an increase in the thermal budget. When the thermal budget increases, it becomes difficult to control the distribution of impurities diffused in the silicon layer, which may cause an undesirable effect on the quality of the semiconductor device.

  In addition, when a glass substrate or a synthetic resin substrate is used as in a liquid crystal display or an organic EL display, for example, it is impossible to anneal the insulating film at a high temperature.

  For this reason, a technique for modifying the film quality at a relatively low temperature by plasma treatment of the silicon oxide film has been proposed (for example, Patent Documents 1 and 2).

WO2002 / 059956 WO2001 / 69665

  The insulating film reforming process for processing the insulating film formed by the CVD method using the plasma of the rare gas and the oxygen gas described in Patent Document 1 and Patent Document 2 described above is good quality while reducing the thermal budget. This is an excellent technique in that a simple insulating film can be manufactured. However, even if such plasma modification treatment is performed, the interface between the silicon and the insulating film cannot be planarized. That is, when an insulating film is formed on silicon by CVD, silicon is first oxidized by heat to form a silicon oxide film. In the process of forming the silicon oxide film, microscopically, since the oxidation rate is different between the (100) plane and the (111) plane of silicon, the silicon oxide film is formed uneven. Then, even if an insulating film is deposited on the uneven silicon oxide film by the CVD method, the shape of the interface does not change. Even if the plasma modification treatment is performed, the interface is not flattened, and the unevenness is not improved. That is, the plasma modification process is hardly expected to have any effect on the first problem.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an insulating film capable of flattening the shape of the interface between silicon and the insulating film as much as possible when the insulating film is formed by the CVD method. It is to provide a forming method.

In order to solve the above problems, a method for forming an insulating film according to the present invention includes a plasma oxidation process step of forming a silicon oxide film as a first insulating film by performing plasma oxidation on silicon exposed on the surface of an object to be processed. ,
A CVD step of forming a second insulating film on the silicon oxide film by a CVD method;
A plasma reforming process for performing a reforming process on the second insulating film using a plasma of a processing gas containing oxygen;
It has.

  In the method for forming an insulating film of the present invention, in a plasma processing apparatus for introducing a microwave into a processing chamber by a planar antenna having a plurality of holes, a processing pressure is in a range of 6.7 Pa to 267 Pa, and the processing gas It is preferable that the flow rate ratio of oxygen to the total flow rate is within a range of 0.1% to 30%. Furthermore, in the method for forming an insulating film of the present invention, it is preferable that the processing pressure in the plasma oxidation processing step is in a range of 6.7 Pa to 67 Pa.

  In the method for forming an insulating film according to the present invention, the plasma reforming treatment step has a treatment pressure in a range of 6.7 Pa to 267 Pa, and a flow rate ratio of oxygen to a total flow rate of the treatment gas is 0.00. It is preferably performed within a range of 1% or more and 30% or less. In this case, it is preferable that the processing pressure in the plasma reforming process is in a range of 6.7 Pa to 67 Pa. Furthermore, it is preferable that the plasma modification step is performed by a plasma processing apparatus that introduces microwaves into the processing chamber using a planar antenna having a plurality of holes.

  In the method for forming an insulating film of the present invention, it is preferable that the second insulating film is formed by a plasma CVD method or a thermal CVD method.

  In the method for forming an insulating film of the present invention, it is preferable that the CVD step and the plasma modification treatment step are repeated a plurality of times.

  In the method for forming an insulating film of the present invention, it is preferable that the processing temperature in the plasma oxidation treatment step and the plasma modification treatment step is in a range of 200 ° C. or more and 600 ° C. or less.

  In the insulating film forming method of the present invention, it is preferable that the plasma oxidation treatment step and the plasma modification treatment step are performed in the same chamber.

  In the insulating film forming method of the present invention, it is preferable that an interface between the silicon oxide film and the silicon formed in the plasma oxidation treatment step is flat.

  In the method for forming an insulating film of the present invention, the thickness of the first insulating film is in the range of 3 nm to 10 nm, and the thickness of the second insulating film is in the range of 3 nm to 10 nm. Preferably there is.

In the insulating film forming method of the present invention, the second insulating film is preferably a silicon oxide film deposited by a CVD method using dichlorosilane and N ₂ O as source gases.

The computer-readable storage medium of the present invention is a computer-readable storage medium storing a control program that runs on a computer,
In the processing system having a plurality of processing chambers for performing predetermined processing on the target object during execution, the control program performs plasma oxidation on the silicon exposed on the surface of the target object and performs first insulation A plasma oxidation process for forming a silicon oxide film as a film; a CVD process for forming a second insulating film on the silicon oxide film by a CVD method; and a process including oxygen for the second insulating film A computer controls the processing system so that a method for forming an insulating film including a plasma reforming process step of performing a reforming process using a plasma of gas is performed.

  A processing system according to the present invention includes a first processing chamber that performs a first process on a target object, and a second process that performs a second process different from the first process on the target object. A processing system having a processing chamber and a third processing chamber that performs a third processing different from the second processing on an object to be processed, wherein the first processing chamber includes the first processing chamber. In this process, silicon exposed on the surface of the object to be processed is subjected to plasma oxidation to form a silicon oxide film as a first insulating film. Next, in the second process chamber, the second process is performed as the second process. A second insulating film is formed on the silicon oxide film by a CVD method. Next, in the third processing chamber, as the third processing, a plasma of a processing gas containing oxygen with respect to the second insulating film. Each process is performed so that plasma reforming treatment is performed using And a control unit for controlling the chamber. In this case, it is preferable that the first processing chamber and the third processing chamber are the same processing chamber.

  According to the insulating film forming method of the present invention, prior to the CVD process, the silicon surface is subjected to plasma oxidation to form a silicon oxide film as a first insulating film so that the interface with silicon becomes flat, By forming the second insulating film on the silicon oxide film by CVD, an increase in interface state density due to accumulation of fixed charges near the silicon / insulating film interface can be suppressed. In addition, by performing plasma modification treatment on the second insulating film, the film quality of the second insulating film becomes dense, and a high-quality insulating film with few impurities and dangling bonds can be obtained. Therefore, according to the method for forming an insulating film of the present invention, it becomes possible to secure carrier mobility in the vicinity of the silicon / insulating film interface, and improve the electrical characteristics of the device such as the operation speed of the transistor, for example. By improving the film quality, a highly reliable device can be manufactured.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a substrate processing system in which an insulating film forming method according to an embodiment of the present invention is performed will be described with reference to FIG. FIG. 1 shows, for example, a substrate process configured to perform various processes such as a plasma oxidation process, a film forming process, and a modification process on a semiconductor wafer (hereinafter simply referred to as “wafer”) W as a substrate. 1 is a schematic configuration diagram showing a system 200. FIG. The substrate processing system 200 is configured as a cluster tool having a multi-chamber structure.

  The substrate processing system 200 has four process modules 101a, 101b, 101c, and 101d that perform various processes on the wafer W as main components, and a gate valve G1 for these process modules 101a to 101d. The connected vacuum side transfer chamber 103, the two load lock chambers 105a and 105b connected to the vacuum side transfer chamber 103 via the gate valve G2, and the gate valve for these two load lock chambers 105a and 105b And a loader unit 107 connected via G3.

  The four process modules 101a to 101d are processing apparatuses that perform processing such as plasma oxidation processing, CVD processing, and plasma modification processing on the wafer W, for example. The process modules 101a to 101d may perform the same processing on the wafer W, or may perform different processing. In the present embodiment, at least in the process modules 101a to 101d, a plasma oxidation process for forming a silicon oxide film by oxidizing silicon of the wafer W, a film forming process by a CVD method, and a film forming process are used. A plasma modification process is performed in which plasma is applied to the silicon oxide film to perform modification.

  The vacuum-side transfer chamber 103 configured to be evacuated is provided with a transfer device 109 as a first substrate transfer device that transfers the wafer W to the process modules 101a to 101d and the load lock chambers 105a and 105b. ing. The transfer device 109 has a pair of transfer arm portions 111a and 111b arranged to face each other. Each of the transfer arm portions 111a and 111b is configured to bend and stretch and turn about the same rotation axis. Further, forks 113a and 113b for mounting and holding the wafer W are provided at the tips of the transfer arm portions 111a and 111b, respectively. The transfer device 109 transfers the wafer W between the process modules 101a to 101d or between the process modules 101a to 101d and the load lock chambers 105a and 105b with the wafer W placed on the forks 113a and 113b. I do.

  In the load lock chambers 105a and 105b, mounting tables 106a and 106b for mounting the wafer W are provided, respectively. The load lock chambers 105a and 105b are configured to be switched between a vacuum state and an air release state. The wafer W is transferred between the vacuum-side transfer chamber 103 and the atmosphere-side transfer chamber 119 (described later) via the loading tables 106a and 106b of the load lock chambers 105a and 105b.

  The loader unit 107 includes an atmosphere-side transfer chamber 119 provided with a transfer device 117 as a second substrate transfer device for transferring the wafer W, and three load ports LP disposed adjacent to the atmosphere-side transfer chamber 119. And an orienter 121 as a position measuring device for measuring the position of the wafer W, which is disposed adjacent to the other side surface of the atmosphere-side transfer chamber 119.

  The atmosphere-side transfer chamber 119 includes, for example, a circulation facility (not shown) that forms a clean environment by flowing down nitrogen gas or clean air, and the clean environment is maintained. The atmosphere-side transfer chamber 119 has a rectangular shape in plan view, and a guide rail 123 is provided along the longitudinal direction thereof. A conveying device 117 is supported on the guide rail 123 so as to be slidable. That is, the transport device 117 is configured to be movable in the X direction along the guide rail 123 by a drive mechanism (not shown). The transfer device 117 has a pair of transfer arm portions 125a and 125b arranged in two upper and lower stages. Each of the transfer arm portions 125a and 125b is configured to be able to bend and stretch and turn. Forks 127a and 127b as holding members for mounting and holding the wafer W are provided at the tips of the transfer arm portions 125a and 125b, respectively. The transfer device 117 transfers the wafer W between the wafer cassette CR of the load port LP, the load lock chambers 105a and 105b, and the orienter 121 in a state where the wafer W is placed on the forks 127a and 127b. Do.

  The load port LP can mount the wafer cassette CR. The wafer cassette CR is configured so that a plurality of wafers W can be placed and accommodated in multiple stages at the same interval.

  The orienter 121 includes a rotating plate 133 that is rotated by a drive motor (not shown) and an optical sensor 135 that is provided at the outer peripheral position of the rotating plate 133 and detects the peripheral edge of the wafer W.

  In the substrate processing system 200 having the above-described configuration, the plasma oxidation process, the CVD process, and the plasma modification process are performed on the wafer W according to the following procedure. First, using the fork 127 of the transfer device 117 in the atmosphere-side transfer chamber 119, one wafer W is taken out from the wafer cassette CR of the load port LP, aligned with the orienter 121, and then loaded into the load lock chamber 105 a (or 105 b). ). In the load lock chamber 105a (or 105b) in a state where the wafer W is mounted on the mounting table 106a (or 106b), the gate valve G3 is closed and the inside is evacuated to a vacuum state. Thereafter, the gate valve G2 is opened, and the wafer W is carried out of the load lock chamber 105a (or 105b) by the fork 113 of the transfer device 109 in the vacuum side transfer chamber 103, and is transferred into any of the process modules 101a to 101d. .

  In the present embodiment, for example, the process module 101a is configured to perform plasma oxidation processing for oxidizing silicon on the surface of the wafer W. Further, the process modules 101b and 101c are configured such that a CVD process for forming an insulating film such as a silicon oxide film on the wafer W can be performed. Further, the process module 101d is configured such that after the insulating film is formed, a plasma reforming process for modifying the insulating film can be performed. In the process modules 101a and 101d, both the plasma oxidation process and the plasma modification process may be performed.

  The wafer W carried out of the load lock chamber 105a (or 105b) by the transfer device 109 is first carried into the process module 101a, and after the gate valve G1 is closed, plasma oxidation processing is performed on the wafer W.

  Next, the gate valve G1 is opened, and the wafer W on which the silicon oxide film is formed is carried into one of the process modules 101b and 101c by the transfer device 109 from the process module 101a in a vacuum state. Then, after the gate valve G1 is closed, the CVD process is performed on the wafer W. An insulating film is deposited on the silicon oxide film by the CVD process.

  Next, the gate valve G1 is opened, and the wafer W on which an insulating film is formed by CVD is transferred from the process module 101b (or 101c) to the process module 101d by the transfer device 109 in a vacuum state. Then, after the gate valve G1 is closed, a plasma reforming process is performed on the insulating film. Next, the gate valve G1 of the process module 101d is opened, and the plasma-modified wafer W is taken out by the transfer device 109 and loaded into the load lock chamber 105a (or 105b). Then, the processed wafer W is stored in the wafer cassette CR of the load port LP in the reverse procedure to the above, and the processing for one wafer W in the substrate processing system 200 is completed. In addition, as long as the arrangement | positioning of each processing apparatus in the substrate processing system 200 is an arrangement | positioning which can process efficiently, what kind of arrangement | positioning structure may be sufficient as it. Furthermore, the number of process modules in the substrate processing system 200 is not limited to four, and may be five or more.

  FIG. 2 is a cross-sectional view schematically showing a schematic configuration of a plasma processing apparatus 100 that can be commonly used for plasma oxidation processing and plasma modification processing performed in the substrate processing system 200. FIG. 3 is a plan view showing a planar antenna of the plasma processing apparatus 100 of FIG.

The plasma processing apparatus 100 generates plasma by introducing microwaves into a processing chamber using a planar antenna having a plurality of slot-shaped holes, particularly RLSA (Radial Line Slot Antenna). In addition, it is configured as an RLSA microwave plasma processing apparatus capable of generating microwave-excited plasma having a low electron temperature. In the plasma processing apparatus 100, a plasma having a plasma density of 1 × 10 ^{10 to} 5 × 10 ¹² / cm ³ and a low electron temperature of 0.7 to 2 eV (particularly 1.1 eV or less in the vicinity of the wafer W) A process that does not damage the wafer W is possible. Therefore, the plasma processing apparatus 100 uses a plasma oxidation process in which silicon is oxidized to form a silicon oxide film (for example, SiO ₂ film) or a silicon oxide film (for example, SiO ₂ film) formed by a CVD method in the manufacturing process of various semiconductor devices. ₂ films) can be suitably used for the purpose of modifying without plasma damage.

  The plasma processing apparatus 100 includes, as main components, an airtight chamber (processing chamber) 1, a gas supply mechanism 18 for supplying gas into the chamber 1, and an exhaust mechanism for evacuating the chamber 1 under reduced pressure. An exhaust device 24, a microwave introduction mechanism 27 for introducing a microwave into the chamber 1, and a control unit 50 for controlling each component of the plasma processing apparatus 100. Yes.

  The chamber 1 is formed of a substantially cylindrical container that is grounded. The chamber 1 may be formed by a rectangular tube-shaped container. The chamber 1 has a bottom wall 1a and a side wall 1b made of a material such as aluminum.

  Inside the chamber 1 is provided a mounting table 2 for horizontally supporting a wafer W as an object to be processed. The mounting table 2 is made of a material having high thermal conductivity, such as ceramics such as AlN. The mounting table 2 is supported by a cylindrical support member 3 extending upward from the center of the bottom of the exhaust chamber 11. The support member 3 is made of ceramics such as AlN, for example.

Further, the mounting table 2 is provided with a cover ring 4 that covers the outer edge portion thereof and guides the wafer W. The cover ring 4 is an annular member made of a material such as quartz, AlN, Al ₂ O ₃ , or SiN.

  In addition, a resistance heating type heater 5 as a temperature adjusting mechanism is embedded in the mounting table 2. The heater 5 is heated by the heater power supply 5a to heat the mounting table 2 and uniformly heats the wafer W, which is a substrate to be processed, with the heat.

  The mounting table 2 is provided with a thermocouple (TC) 6. By measuring the temperature with the thermocouple 6, the heating temperature of the wafer W can be controlled in a range from room temperature to 900 ° C., for example.

  The mounting table 2 is provided with wafer support pins (not shown) for supporting the wafer W and raising and lowering it. Each wafer support pin is provided so as to protrude and retract with respect to the surface of the mounting table 2.

  A cylindrical liner 7 made of quartz is provided on the inner periphery of the chamber 1. In addition, a quartz baffle plate 8 having a large number of exhaust holes 8 a is annularly provided on the outer peripheral side of the mounting table 2 in order to uniformly exhaust the inside of the chamber 1. The baffle plate 8 is supported by a plurality of support columns 9.

  A circular opening 10 is formed at a substantially central portion of the bottom wall 1 a of the chamber 1. An exhaust chamber 11 that communicates with the opening 10 and protrudes downward is provided on the bottom wall 1a. An exhaust pipe 12 is connected to the exhaust chamber 11 and is connected to an exhaust device 24 via the exhaust pipe 12.

  An annular upper plate 13 is joined to the upper portion of the chamber 1. The inner periphery of the upper plate 13 protrudes toward the inner side (chamber inner space) to form an annular support portion 13a.

  An annular gas inlet 15 is provided on the side wall 1 b of the chamber 1. The gas introduction unit 15 is connected to a gas supply mechanism 18 that supplies an oxygen-containing gas and a plasma excitation gas. The gas introduction part 15 may be provided in a nozzle shape or a shower shape.

  Further, on the side wall 1b of the chamber 1, a loading / unloading port 16 for loading / unloading the wafer W between the plasma processing apparatus 100 and the transfer chamber 103 (see FIG. 1) adjacent thereto is provided, and this loading / unloading port. A gate valve G1 for opening and closing 16 is provided.

  The gas supply mechanism 18 includes, for example, an inert gas supply source 19a, an oxygen-containing gas supply source 19b, and a hydrogen gas supply source 19c. The gas supply mechanism 18 includes, as gas supply sources (not shown) other than the above, for example, a purge gas supply source used when replacing the atmosphere in the chamber 1, a cleaning gas supply source used when cleaning the inside of the chamber 1, and the like. It may be.

As the inert gas, for example, N ₂ gas or rare gas can be used. As the rare gas, for example, Ar gas, Kr gas, Xe gas, He gas, or the like can be used. Among these, it is particularly preferable to use Ar gas because it is economical. As the oxygen-containing gas, for example, oxygen gas (O ₂ ), water vapor (H ₂ O), nitrogen monoxide (NO), dinitrogen monoxide (N ₂ O), or the like can be used.

  The inert gas, oxygen-containing gas, and hydrogen gas reach the gas introduction unit 15 through the gas line 20 from the inert gas supply source 19a, the oxygen-containing gas supply source 19b, and the hydrogen gas supply source 19c of the gas supply mechanism 18. The gas is introduced into the chamber 1 from the gas introduction part 15. Each gas line 20 connected to each gas supply source is provided with a mass flow controller 21 and front and rear opening / closing valves 22. With such a configuration of the gas supply mechanism 18, the supplied gas can be switched and the flow rate can be controlled.

  The exhaust device 24 as an exhaust mechanism includes a high-speed vacuum pump such as a turbo molecular pump. As described above, the exhaust device 24 is connected to the exhaust chamber 11 of the chamber 1 through the exhaust pipe 12. The gas in the chamber 1 flows uniformly into the space 11a of the exhaust chamber 11, and is further exhausted to the outside through the exhaust pipe 12 by operating the exhaust device 24 from the space 11a. Thereby, the inside of the chamber 1 can be depressurized at a high speed to a predetermined degree of vacuum, for example, 0.133 Pa.

  Next, the configuration of the microwave introduction mechanism 27 will be described. The microwave introduction mechanism 27 includes a transmission plate 28, a planar antenna 31, a slow wave material 33, a cover 34, a waveguide 37, a matching circuit 38, and a microwave generator 39 as main components.

The transmission plate 28 that transmits microwaves is disposed on a support portion 13 a that protrudes to the inner peripheral side of the upper plate 13. The transmission plate 28 is made of a dielectric, for example, ceramics such as quartz, Al ₂ O ₃ , and AlN. A gap between the transmission plate 28 and the support portion 13a is hermetically sealed through a seal member 29. Therefore, the inside of the chamber 1 is kept airtight.

  The planar antenna 31 is provided above the transmission plate 28 so as to face the mounting table 2. The planar antenna 31 has a disk shape. The shape of the planar antenna 31 is not limited to a disk shape, and may be a square plate shape, for example. The planar antenna 31 is locked to the upper end of the upper plate 13.

  The planar antenna 31 is made of, for example, a copper plate, an aluminum plate, a nickel plate, or an alloy plate of these metals whose surface is plated with gold or silver. The planar antenna 31 has a number of slot-shaped microwave radiation holes 32 that radiate microwaves. The microwave radiation holes 32 are formed through the planar antenna 31 in a predetermined pattern.

  Each microwave radiation hole 32 has an elongated rectangular shape (slot shape), for example, as shown in FIG. And typically, the adjacent microwave radiation holes 32 are arranged in a “T” shape. Further, the microwave radiation holes 32 arranged in combination in a predetermined shape (for example, T shape) are further arranged concentrically as a whole.

  The length and arrangement interval of the microwave radiation holes 32 are determined according to the wavelength (λg) of the microwave. For example, the interval between the microwave radiation holes 32 is arranged to be λg / 4, λg / 2, or λg. In FIG. 3, the interval between adjacent microwave radiation holes 32 formed concentrically is indicated by Δr. Note that the microwave radiation hole 32 may have another shape such as a circular shape or an arc shape. Furthermore, the arrangement form of the microwave radiation holes 32 is not particularly limited, and may be arranged in a spiral shape, a radial shape, or the like in addition to a concentric shape.

  A slow wave material 33 having a dielectric constant larger than that of a vacuum is provided on the upper surface of the planar antenna 31. The slow wave material 33 has a function of adjusting the wavelength of the microwave to be short since the wavelength of the microwave is increased in a vacuum, and the microwave can be efficiently introduced into the chamber 1 from the microwave radiation hole 32. It is configured as follows. As the material of the slow wave material 33, for example, quartz, polytetrafluoroethylene resin, polyimide resin or the like can be used.

  Note that the microwave can be efficiently introduced into the chamber 1, although the planar antenna 31 and the transmission plate 28 and the slow wave material 33 and the planar antenna 31 may be in contact with each other or separated from each other. In doing so, it is preferable to contact them.

  A cover 34 is provided on the upper portion of the chamber 1 so as to cover the planar antenna 31 and the slow wave material 33, and constitutes a planar waveguide with the planar antenna 31. The cover 34 is made of a metal material such as aluminum or stainless steel. The upper end of the upper plate 13 and the cover 34 are sealed by a seal member 35. A cooling water channel 34 a is formed inside the cover 34. By allowing the cooling water to flow through the cooling water flow path 34a, the cover 34, the slow wave material 33, the planar antenna 31 and the transmission plate 28 can be cooled. The cover 34 is grounded.

  An opening 36 is formed at the center of the upper wall (ceiling) of the cover 34, and a waveguide 37 is connected to the opening 36. A microwave generator 39 that generates microwaves is connected to the other end of the waveguide 37 via a matching circuit 38.

  The waveguide 37 is connected to a coaxial waveguide 37a having a circular cross section extending upward from the opening 36 of the cover 34, and an upper end portion of the coaxial waveguide 37a via a mode converter 40. And a rectangular waveguide 37b extending in the horizontal direction. The mode converter 40 has a function of converting the microwave propagating in the TE mode in the rectangular waveguide 37b into the TEM mode.

  An inner conductor 41 extends at the center of the coaxial waveguide 37a. The inner conductor 41 is connected and fixed to the center of the planar antenna 31 at its lower end. With such a structure, the microwave is efficiently and uniformly propagated radially and uniformly to the planar antenna 31 via the inner conductor 41 of the coaxial waveguide 37a.

  With the microwave introduction mechanism 27 configured as described above, the microwave generated by the microwave generator 39 is propagated to the planar antenna 31 via the waveguide 37 and further introduced into the chamber 1 via the transmission plate 28. It has come to be. For example, 2.45 GHz is preferably used as the frequency of the microwave, and 8.35 GHz, 1.98 GHz, or the like can also be used.

  Each component of the plasma processing apparatus 100 is connected to and controlled by the controller 50. The control unit 50 includes a computer, and includes a process controller 51 having a CPU, a user interface 52 connected to the process controller 51, and a storage unit 53, as shown in FIG. In the plasma processing apparatus 100, the process controller 51 is a component related to process conditions such as temperature, pressure, gas flow rate, and microwave output (for example, the heater power supply 5a, the gas supply mechanism 18, the exhaust device 24, the microwave). This is a control means for controlling the generator 39 and the like in an integrated manner.

  The user interface 52 includes a keyboard on which a process manager manages command input to manage the plasma processing apparatus 100, a display that visualizes and displays the operating status of the plasma processing apparatus 100, and the like. The storage unit 53 stores a recipe in which a control program (software) for realizing various processes executed by the plasma processing apparatus 100 under the control of the process controller 51 and processing condition data are recorded. Yes.

  If necessary, an arbitrary recipe is called from the storage unit 53 according to an instruction from the user interface 52 and is executed by the process controller 51, so that the process controller 51 controls the inside of the chamber 1 of the plasma processing apparatus 100. The desired process is performed. The recipes such as the control program and processing condition data may be stored in a computer-readable storage medium such as a CD-ROM, a hard disk, a flexible disk, a flash memory, a DVD, or a Blu-ray disk. Alternatively, it may be transmitted from other devices as needed via, for example, a dedicated line and used online.

  In the plasma processing apparatus 100 configured as described above, plasma processing with less thermal budget can be performed at a low temperature of 600 ° C. or lower, preferably 500 ° C. or lower, free of damage to the underlying film or the like. In addition, since the plasma processing apparatus 100 is excellent in plasma uniformity, it is possible to achieve processing uniformity within a plane even for a large-diameter wafer W.

  FIG. 5 shows a schematic configuration example of a single wafer CVD film forming apparatus 300 applicable as the process modules 101b and 101c. The single wafer CVD film forming apparatus 300 includes a substantially cylindrical processing container 301 that is airtight. In the processing container 301, a susceptor 303 for horizontally supporting a wafer W as an object to be processed is provided. The susceptor 303 is supported by a cylindrical support member 305. A heater 307 is embedded in the susceptor 303. The heater 307 is supplied with power from the heater power source 309 to heat the wafer W to a predetermined temperature.

A shower head 311 is provided on the open / close top wall 301 a of the processing container 301. The shower head 311 has a gas diffusion space 311a inside. In addition, a large number of gas discharge holes 313 communicating with the gas diffusion space 311 a are formed on the lower surface of the shower head 311. A gas supply pipe 315 communicating with the gas diffusion space 311a is connected to the center of the shower head 311. This gas supply pipe 315 is provided with a film forming source gas such as dichlorosilane, dinitrogen monoxide (N ₂ O), or a processing container via a mass flow controller (MFC) 317 and valves 318a and 318b arranged before and after the mass flow controller (MFC) 317. It is connected to a gas supply source 319 for supplying a purge gas for replacing the atmosphere in 301. Then, the film forming source gas and the like are supplied from the gas supply source 319 to the shower head 311 via the gas supply pipe 315 and the mass flow controller 317.

  An exhaust hole 331 is formed in the bottom wall 301 b of the processing container 301, and an exhaust device 335 is connected to the exhaust hole 331 through an exhaust pipe 333. The exhaust device 335 is operated so that the inside of the processing vessel 301 can be depressurized to a predetermined vacuum level. Note that, by supplying high frequency power from a high frequency power source (not shown) to the shower head 311, the source gas supplied into the processing container 301 through the shower head 311 can be converted into plasma to form a film.

  Further, a loading / unloading port 337 for loading / unloading the wafer W is provided on the side wall 301 c of the processing container 301, and the wafer W is loaded / unloaded through the loading / unloading port 337. The loading / unloading port 337 is opened and closed by the gate valve G1.

In the single wafer CVD film forming apparatus 300 configured as described above, the source gas is supplied from the shower head 311 toward the wafer W while the wafer W is heated by the heater 307 while the wafer W is placed on the susceptor 303. As a result, a thin film of, for example, a SiO ₂ film can be formed on the surface of the wafer W by the CVD method.

  The single wafer CVD film forming apparatus 300 having the above configuration is also controlled by the control unit 50 (see FIG. 4). The CVD film forming apparatus is not limited to a single wafer type, and a batch type LP (Low Pressure) CVD film forming apparatus can also be used.

  Next, a method for forming an insulating film including a plasma oxidation process and a plasma modification process performed in the substrate processing system 200 will be described with reference to FIGS. FIG. 6 shows a step of plasma-oxidizing silicon to form a first insulating film, a step of forming a second insulating film on the first insulating film, and a step of forming the second insulating film. FIG. 7 is a flow diagram showing a flow of a method for forming an insulating film including a step of modifying, and FIG.

  The insulating film forming method of the present embodiment is performed by the procedure from step S1 to step S7 shown in FIG. 6, for example. First, in step S1 of FIG. 6, the wafer W to be processed is loaded into the plasma processing apparatus 100 (process module 101a) by the transfer apparatus 109 in the vacuum-side transfer chamber 103 according to the above procedure. Next, in step S2, a plasma oxidation process is performed on the silicon layer 201 exposed on the surface of the wafer W as shown in FIG. By this plasma oxidation treatment, as shown in FIG. 7B, the surface of the silicon layer 201 is oxidized to form a silicon oxide film 202 as a first insulating film with a predetermined thickness. The plasma oxidation treatment is performed according to the following procedure and conditions.

[Plasma oxidation treatment procedure]
First, while evacuating the chamber 1 of the plasma processing apparatus 100 under reduced pressure, the inert gas supply source 19a and the oxygen-containing gas supply source 19b of the gas supply mechanism 18 are respectively introduced with a rare gas and an oxygen-containing gas at a predetermined flow rate. It is introduced into the chamber 1 through the part 15. In this way, the inside of the chamber 1 is adjusted to a predetermined pressure.

  Next, a microwave having a predetermined frequency, for example, 2.45 GHz, generated by the microwave generator 39 is guided to the waveguide 37 via the matching circuit 38. The microwave guided to the waveguide 37 sequentially passes through the rectangular waveguide 37 b and the coaxial waveguide 37 a and is supplied to the planar antenna 31 through the inner conductor 41. That is, the microwave propagates in the TE mode in the rectangular waveguide 37b, and the TE mode microwave is converted into the TEM mode by the mode converter 40, and the inside of the coaxial waveguide 37a is directed to the planar antenna 31. Will be propagated. Then, the microwave is radiated from the slot-shaped microwave radiation hole 32 formed through the planar antenna 31 to the space above the wafer W in the chamber 1 through the transmission plate 28. The microwave output at this time can be selected according to the purpose from the range of 2000 W or more and 5000 W or less, for example, when processing a wafer W having a diameter of 200 mm or more.

An electromagnetic field is formed in the chamber 1 by the microwave radiated from the planar antenna 31 through the transmission plate 28 to the chamber 1, and the inert gas and the oxygen-containing gas are turned into plasma, respectively. The microwave-excited plasma has a high density of about 1 × 10 ^{10 to} 5 × 10 ¹² / cm ³ and a vicinity of the wafer W when microwaves are radiated from a large number of microwave radiation holes 32 of the planar antenna 31. Then, it becomes a low electron temperature plasma of about 1.1 eV or less. The microwave-excited high-density plasma formed in this way is a plasma mainly composed of, for example, O ( ¹ D ₂ ) radicals and O ₂ ⁺ ions as active species in the plasma. The silicon layer 201 is oxidized to form a silicon oxide film 202 with little plasma damage caused by ions or the like.

[Plasma oxidation treatment conditions]
As a processing gas for the plasma oxidation treatment, it is preferable to use a gas containing a rare gas and an oxygen-containing gas. It is preferable to use Ar gas as the rare gas and O ₂ gas as the oxygen-containing gas. In this case, the volumetric flow ratio of O ₂ gas to the total process gas (O ₂ gas flow rate / total process gas flow rate percentage of) is, O ₂ ⁺ ions and O (1 ^D ₂₎ radicals and predominantly as the active species in the plasma In view of this, it is preferable to be within the range of 0.1% to 30%, and more preferably within the range of 0.5% to 3%. For example, when processing a wafer W having a diameter of 200 mm or more, the flow rate of Ar gas is in the range of 50 mL / min (sccm) to 5000 mL / min (sccm), and the flow rate of O ₂ gas is 0.05 mL / min (sccm). ) The flow rate ratio can be set within the range of 1000 mL / min (sccm) or less.

The treatment pressure is preferably in the range of 6.7 Pa to 267 Pa, and preferably 6.7 Pa to 67 Pa from the viewpoint of predominating O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals as active species in the plasma. Within the range is more preferable.

The microwave power density is in the range of 0.5 W / cm ² or more and 3 W / cm ² or less from the viewpoint of efficiently generating O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals as active species in the plasma. It is possible to be within the range of 0.51 W / cm ² or more and 2.56 W / cm ² or less. The microwave power density means the microwave power supplied per 1 cm ² area of the transmission plate 28 (the same applies hereinafter). For example, when processing a wafer W having a diameter of 200 mm or more, it is preferable that the microwave power is in the range of 1000 W to 5000 W.

  Further, the heating temperature of the wafer W is preferably set, for example, in the range of 200 ° C. or more and 600 ° C. or less, and more preferably in the range of 400 ° C. or more and 600 ° C. or less as the temperature of the mounting table 2.

Thickness _{T 1} of the silicon oxide film 202 is formed on the silicon layer 201 of the wafer W by the plasma oxidation treatment, in view of enhancing the flatness of the interface of the silicon layer 201 and the silicon oxide film 202, 3 nm or more 10nm within the following ranges Is preferable, and the range of 4 nm to 8 nm is more preferable.

  The above conditions are stored as a recipe in the storage unit 53 of the control unit 50. The process controller 51 reads the recipe and sends a control signal to each component of the plasma processing apparatus 100, such as the gas supply mechanism 18, the exhaust device 24, the microwave generator 39, the heater power supply 5a, etc. Plasma oxidation treatment is performed under conditions.

  Next, in step S3, the wafer W on which the silicon oxide film is formed is transferred to the single wafer CVD film forming apparatus 300 (process module 101b or 101c) by the transfer device 109 in the vacuum side transfer chamber 103. This transfer is performed in a vacuum state by the transfer device 109 in the vacuum side transfer chamber 103.

  Next, in step S4, as shown in FIG. 7C, a film forming process by a CVD method is performed on the silicon oxide film 202 formed on the surface of the wafer W. As a result, as shown in FIG. 7D, a silicon oxide film 203 as a second insulating film is formed over the silicon oxide film 202. As this CVD method, a thermal CVD method is used in the present embodiment using the substrate processing system 200, but it is possible to form a film by a method such as a plasma CVD method, a low pressure CVD method, or an atmospheric pressure CVD method. . The film forming method may be a single wafer type or a batch type.

Thickness T ₂ of the silicon oxide film 203 is stacked on the silicon oxide film 202 of the wafer W by a film forming process by the CVD method, from the viewpoint of increasing the modification effect with respect to the film thickness direction, 3 nm or more 10nm following Within the range, the range of 4 nm or more and 8 nm or less is more preferable.

  Next, in step S5, the wafer W on which the silicon oxide film 202 and the silicon oxide film 203 are formed is transferred to a plasma processing apparatus 100 (process module 101d) as a plasma modification processing apparatus. This transfer is performed in a vacuum state by the transfer device 109 in the vacuum side transfer chamber 103. Next, in step S6, as shown in FIG. 7E, a plasma reforming process is performed on the silicon oxide film 203. Since the procedure of the plasma modification process performed using the plasma processing apparatus 100 is in accordance with the procedure of the plasma oxidation process, description thereof is omitted here. The conditions for the plasma reforming process in step S6 are as follows.

[Plasma reforming treatment conditions]
As a processing gas for the plasma reforming treatment, it is preferable to use a gas containing a rare gas and an oxygen-containing gas. It is preferable to use Ar gas as the rare gas and O ₂ gas as the oxygen-containing gas. In this case, the volumetric flow ratio of O ₂ gas to the total process gas (O ₂ gas flow rate / total process gas flow rate percentage of) is, O ₂ ⁺ ions and O (1 ^D ₂₎ radicals and predominantly as the active species in the plasma In view of the above, it is preferable to be in the range of 0.1% to 30%, and more preferable to be in the range of 0.1% to 5%. For example, when processing a wafer W having a diameter of 200 mm or more, the flow rate of Ar gas is in the range of 500 mL / min (sccm) to 5000 mL / min (sccm), and the flow rate of O ₂ gas is 0.5 mL / min (sccm). ) The flow rate ratio can be set within the range of 1000 mL / min (sccm) or less.

The treatment pressure is preferably in the range of 6.7 Pa to 267 Pa, and preferably 6.7 Pa to 67 Pa from the viewpoint of predominating O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals as active species in the plasma. Within the range is more preferable.

Further, the power density of the microwave is 0. from the viewpoint of efficiently generating O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals as active species in the plasma and repairing defects in the silicon oxide film 203. It is preferable to be in the range of 51 W / cm ² or more and 2.56 W / cm ² or less. For example, when processing a wafer W having a diameter of 200 mm or more, it is preferable that the microwave power is in the range of 1000 W to 5000 W.

  Further, the heating temperature of the wafer W is preferably set, for example, in the range of 200 ° C. or more and 600 ° C. or less, and more preferably in the range of 400 ° C. or more and 600 ° C. or less as the temperature of the mounting table 2.

  The above conditions are stored as a recipe in the storage unit 53 of the control unit 50. The process controller 51 reads the recipe and sends a control signal to each component of the plasma processing apparatus 100, such as the gas supply mechanism 18, the exhaust device 24, the microwave generator 39, the heater power supply 5a, etc. Plasma reforming treatment is performed under conditions.

  After the plasma reforming process in step S6 is completed, the processed wafer W is unloaded from the plasma processing apparatus 100 (process module 101d) by the transfer apparatus 109 in the vacuum transfer chamber 103 in step S7, and the load port is processed according to the above procedure. Housed in LP wafer cassette CR.

  As described above, in the substrate processing system 200, the silicon oxidation treatment by the plasma oxidation treatment method, the silicon oxide film 203 formation treatment by the CVD method, and the silicon oxide film 203 modification treatment are continuously performed under vacuum. Can be implemented. In the process modules 101a and 101d, both the plasma oxidation process in step S2 and the plasma modification process in step S6 may be performed.

[Action]
Next, an operation mechanism of the silicon oxide film forming method performed in the substrate processing system 200 will be described with reference to FIG. A silicon oxide film 203 formed on the surface of the silicon layer 201 by a normal CVD method is deposited by heat. In the initial stage of film formation, the silicon surface is first thermally oxidized to form a silicon oxide film. However, since silicon has a plane orientation, fine irregularities are formed at the interface with the silicon layer 201 as shown in FIG. In addition, many defects are formed near the boundary (SiO ₂ / Si interface) between the silicon oxide film 203 and the silicon layer 201, and the interface state density increases. As a result, the mobility of carriers (electrons and holes) decreases and, for example, in the case of a transistor, the operation speed decreases, or the leakage current increases and the electrical performance of the device decreases.

In the method for forming an insulating film according to this embodiment, prior to the CVD process, first, a plasma oxidation process is performed on the surface of the silicon layer 201 using a plasma processing apparatus 100 at a low pressure and a low oxygen partial pressure. The boundary (SiO ₂ / Si interface) between the silicon oxide film 202 thus formed and the silicon layer 201 can be formed extremely flat as shown in FIG. 8B. For this reason, defects are reduced near the boundary (SiO ₂ / Si interface) between the silicon oxide film 202 and the silicon layer 201, and an increase in interface state density is suppressed. Then, a silicon oxide film 203 is formed on the silicon oxide film 202 with a predetermined thickness by a CVD method.

FIG. 9 schematically shows a chemical change caused in the silicon oxide film by the plasma modification process. Further, when plasma of a processing gas containing oxygen is generated using the plasma processing apparatus 100, the oxidation active species in the plasma changes depending on the processing pressure. Specifically, O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals in plasma increase under low pressure conditions (267 Pa or less, preferably 6.7 Pa to 267 Pa, more preferably 6.7 Pa to 67 Pa). To do. O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals have low ability to permeate the silicon oxide film that is the target of the modification treatment. For this reason, when the plasma reforming process is performed under the plasma generation conditions in which these active species are dominant in the plasma, as shown in FIG. 9, O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals are converted into silicon oxide. It penetrates into the film 203 and forms a bond with Si dangling bonds. At this time, unstable impurities such as Cl, H, and OH derived from the film forming raw material in the CVD method contained in the silicon oxide film 203 are replaced with O ₂ ⁺ ions or O ( ¹ D ₂ ) radicals. It is discharged out of the membrane. By such a mechanism, by performing plasma reforming treatment under low pressure conditions, the film quality of the silicon oxide film 203 becomes dense, and the film is modified to a high-quality film with few impurities and dangling bonds.

On the other hand, under high pressure conditions (for example, 333 Pa or more), O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals decrease as active species in the plasma, and O ( ³ P ₂ ) radicals are mainly used instead. Since this O ( ³ P ₂ ) radical has a property of passing through the silicon oxide film 203, O ₂ ⁺ ions and O ( ¹ ) are generated under plasma generation conditions in which the O ( ³ P ₂ ) radical is dominant. D ₂ ) An excellent reforming effect such as plasma mainly composed of radicals cannot be obtained.

In the method for forming an insulating film according to this embodiment, attention is paid to the change of active species in plasma due to the above processing pressure, and low pressure conditions in which O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals are dominant. By selecting (267 Pa or less) and performing a plasma modification process on the silicon oxide film 203, a high modification effect on the silicon oxide film 203 could be obtained.

In this way, silicon is plasma-oxidized to form a silicon oxide film so that the interface with silicon is extremely flat, and an insulating film is formed on the silicon oxide film by a CVD method. By reforming with plasma containing oxygen, it is possible to improve the film quality so that the interface state density at the SiO ₂ / Si interface is small and dense and has few impurities and dangling bonds. Accordingly, it is possible to form high-quality insulating films (silicon oxide film 202 and silicon oxide film 203) in which the decrease in the mobility of carriers moving through the SiO ₂ / Si interface is suppressed and the electrical performance of the device is improved. . This insulating film is used, for example, as a gate insulating film of a thin film transistor (TFT) element, and can be advantageously used particularly in the range of 5 nm to 1000 nm, preferably in the range of 8 nm to 100 nm.

FIG. 10 is a cross-sectional view showing a schematic configuration of a TFT element 400 to which the insulating film forming method according to the present embodiment can be applied. On the glass substrate 401, a gate electrode 402 made of, for example, polysilicon is partially formed. A thin film of a silicon oxide film 402 a is formed on the surface of the gate electrode 402. A gate insulating film 403 made of silicon dioxide (SiO ₂ ) is formed so as to cover the surface of the gate electrode 402 including the silicon oxide film 402 a and the glass substrate 401. An a-Si (amorphous silicon) film 404 is formed on the gate insulating film 403 as an Si-based film for forming a transistor, and a channel portion 405 is formed on the gate electrode 402. A source electrode 406 and a drain electrode 407 containing a refractory metal material such as molybdenum or tungsten are formed on the a-Si film 404. A passivation film 408 made of silicon nitride (Si ₃ N ₄ ) is formed on the source electrode 406 and the drain electrode 407 to protect the surface of the TFT element 400.

  In the case of applying the insulating film forming method of the present embodiment to the TFT element 400 having the configuration as shown in FIG. 10, after patterning the gate electrode 402 made of polysilicon on the glass substrate 401, the surface is formed. Plasma oxidation is performed using the plasma processing apparatus 100 to form a silicon oxide film 402 a on the surface portion of the gate electrode 402. Next, a gate insulating film 403 is formed by a CVD method so as to cover the surfaces of the gate electrode 402 and the glass substrate 401. Further, the gate insulating film 403 is subjected to plasma modification treatment by using the plasma processing apparatus 100, whereby the silicon oxide film is modified to be dense and low in impurities. The above processing can be performed according to the procedure of step S1 to step S7 in FIG. Thereafter, the film formation and etching are repeated in accordance with a conventional method, and the film formation and pattern formation of the a-Si film 404, the film formation and pattern formation of the source electrode 406 and the drain electrode 407, the film formation of the passivation film 408, and the ITO electrode (illustrated). The TFT element 400 can be formed by forming (omitted).

In the TFT element 400 illustrated in FIG. 10, the surface portion of the gate electrode 402 is subjected to plasma oxidation using the plasma processing apparatus 100 to form the silicon oxide film 402 a, thereby forming the gate insulating film 403. The interface between the subsequent insulating film (silicon oxide film 402a and gate insulating film 403) and the gate electrode 402 (polysilicon) can be made extremely flat. Therefore, defects near the boundary (SiO ₂ / polysilicon interface) between the insulating film (silicon oxide film 402a and gate insulating film 403) and the gate electrode 402 are reduced, and an increase in interface state density is suppressed. Therefore, a decrease in mobility of carriers moving on the interface is suppressed, and the electrical performance of the TFT element 400 can be improved.

  In addition, by performing plasma modification treatment under low pressure conditions using the plasma treatment apparatus 100, the film quality of the gate insulating film 403 becomes dense, and the film can be modified to a high-quality film with few impurities and dangling bonds. . Note that the gate insulating film 403 is preferably formed by a plasma CVD method.

  Next, experimental data on which the present invention is based will be described. Plasma modification processing was performed on the silicon oxide film formed by the thermal CVD method under the following conditions 1 to 4 using the plasma processing apparatus 100 shown in FIG. With respect to the silicon oxide film after modification, the amount of increase in film thickness, the amount of increase in refractive index, and the wet etching rate by 0.125% dilute hydrofluoric acid treatment (30 seconds) were examined. Further, a MOS capacitor is manufactured using the modified silicon oxide film as a gate insulating film, and its electrical characteristics include leakage current density (Jg; −10 MV / cm), insulating film breakdown over time (TDDB; 63%) The amount of change of the electron trap (Δvge; 11 seconds) was examined. For comparison, the same measurement as described above was performed for the case where the modification was not performed, the case where the modification was performed by annealing, and the thermal oxide film. The results are shown in Table 1.

[Reforming condition 1]
Ar gas flow rate: 1000 mL / min (sccm)
O ₂ gas flow rate; 300 mL / min (sccm)
Flow rate ratio (O ₂ / Ar + O ₂ ); 0.23
Processing pressure: 6.7 Pa
Temperature of mounting table 2; 500 ° C
Microwave power: 4000W
Microwave power density: 2.05 W / cm ² (per transmission plate area 1 cm ² )

[Reforming condition 2]
Ar gas flow rate: 1980 mL / min (sccm)
O ₂ gas flow rate: 20 mL / min (sccm)
Flow rate ratio (O ₂ / Ar + O ₂ ); 0.01
Processing pressure: 200 Pa
Temperature of mounting table 2; 500 ° C
Microwave power: 4000W
Microwave power density: 2.05 W / cm ² (per transmission plate area 1 cm ² )

[Reforming condition 3]
Ar gas flow rate: 1200 mL / min (sccm)
O ₂ gas flow rate: 400 mL / min (sccm)
Flow rate ratio (O ₂ / Ar + O ₂ ); 0.25
Processing pressure: 667 Pa
Temperature of mounting table 2; 500 ° C
Microwave power: 4000W
Microwave power density: 2.05 W / cm ² (per transmission plate area 1 cm ² )

[Reforming condition 4]
Ar gas flow rate: 1200 mL / min (sccm)
O ₂ gas flow rate: 370 mL / min (sccm)
H ₂ gas flow rate: 30 mL / min (sccm)
Flow rate ratio (O ₂ / Ar + O ₂ + H ₂ ); 0.23
Flow rate ratio (H ₂ / Ar + O ₂ + H ₂ ); 0.019
Processing pressure: 667 Pa
Temperature of mounting table 2; 500 ° C
Microwave power: 4000W
Microwave power density: 2.05 W / cm ² (per transmission plate area 1 cm ² )

[Annealing treatment conditions]
Atmosphere; N ₂ / O ₂ = 10 / 0.1 L / min
Temperature: 900 ° C
Pressure: 133Pa

[Thermal oxide film formation conditions]
Atmosphere; H ₂ / O ₂ = 450/900 mL / min (sccm)
Temperature: 950 ° C
Pressure: 15000Pa

[Thermal CVD deposition conditions]
SiH ₂ Cl ₂ gas flow rate; 75 mL / min (sccm)
N ₂ O gas flow rate; 150 mL / min (sccm)
Processing pressure: 48Pa
Processing temperature: 780 ° C

  From the results of physical analysis shown in Table 1, when the plasma modification treatment is performed under conditions 1 and 2 as low as 200 Pa or less, the refractive index increases and the wet etching rate decreases. These data indicate that the film quality of the silicon oxide film is improved by the plasma modification treatment, and the film density is increased. In addition, when the wet etching rates of conditions 1 and 2 are compared with the modification treatment by annealing, it is shown that conditions 1 and 2 have a lower etching rate and higher modification effect than thermal annealing modification. It was done.

In addition, when the plasma modification treatment was performed under condition 4, no change in refractive index was observed, and the wet etching rate was almost the same as the modification treatment by annealing. In other words, with respect to the effect of improving the film quality, the plasma modification treatment under condition 4 was the same result as the modification treatment by annealing. However, when the plasma modification treatment was performed under condition 4, the increase in the thickness of the silicon oxide film was noticeable. This was thought to be because the interface between the silicon oxide film formed by the CVD method and the underlying silicon was oxidized by O ( ³ P ₂ ) radicals in the plasma to increase the film thickness.

  From the above results, in the plasma reforming process at a processing pressure of 267 Pa or less, for example, 6.7 Pa or more and 267 Pa or less, the effect of improving the quality of the silicon oxide film formed by the CVD method is higher than the reforming process by annealing. Indicated. On the other hand, in the case of the plasma reforming process under a high pressure condition of 667 Pa, the effect of improving the quality of the silicon oxide film formed by the CVD method is equivalent to the reforming process by annealing. It was found to have an effect.

  According to the results of the electrical characteristic evaluation shown in Table 2, when the plasma reforming process is performed under conditions 1 and 2 where the processing pressure is as low as 200 Pa or less, the leakage current density (Jg) is as high as 667 Pa. Compared to Condition 3 and the modification process by annealing, the process was greatly improved.

FIG. 11 shows the relationship between the processing pressure and the leakage current in the plasma reforming processing under conditions 1 to 3. Here, the annealing modification treatment and the leakage current of the thermal oxide film are also shown. From FIG. 11, it can be seen that when the processing pressure is 267 Pa or less, for example, 6.7 Pa or more and 267 Pa, the leakage current can be suppressed to 2.1 × 10 ⁻⁴ [A / cm ² ] or less. Therefore, when the purpose is to improve the leakage current characteristics, it is preferable to set the processing pressure of the plasma reforming process to 267 Pa or less.

  The dielectric breakdown over time (TDDB) was significantly improved when the plasma modification treatment was performed under conditions 1 to 3 as compared to the modification treatment by annealing. In particular, in the case of the plasma reforming treatment under condition 2, very excellent reliability exceeding the thermal oxide film was shown.

FIG. 12 shows the relationship between the processing pressure of the plasma reforming treatment under conditions 1 to 3 and TDDB. Here, the annealing modification treatment and the leakage current of the thermal oxide film are also shown. From FIG. 12, it can be seen that if the treatment pressure is 533 Pa or less, the TDDB can be 33 [C / cm ² ] or more. Therefore, when the purpose is to improve the TDDB characteristics, it is preferable to set the processing pressure of the plasma reforming treatment to 533 Pa or less, such as 6.7 Pa to 533 Pa, more preferably 400 Pa or less, such as 6.7 Pa to 400 Pa, 267 Pa or less, for example, 6.7 Pa or more and 267 Pa or less is desirable.

FIG. 13 shows the relationship between the O ₂ / (Ar + O ₂ ) ratio and TDDB under conditions 1 to 3. In the plasma reforming treatment, as shown in FIG. 13, by setting the O ₂ / (Ar + O ₂ ) ratio to 0.23 or less, the TDDB characteristics can be effectively improved, and in particular, the O ₂ / (Ar + O ₂ ) ratio. It was found that by setting the ratio to 0.1 or less, high TDDB characteristics exceeding the thermal oxide film can be obtained.

Regarding the amount of change (Δvge) of the electron trap, when the plasma reforming process was performed under conditions 1 and 2, it was almost halved compared to the reforming process by annealing, which was greatly improved. Even when the plasma reforming process was performed under condition 3, the amount of change in the electron trap was slightly reduced compared with the reforming process by annealing. Further, in the plasma reforming treatment, as shown in Table 2, it was found that the Δvge characteristic can be effectively improved by setting the O ₂ / (Ar + O ₂ ) ratio to 0.23 or less.

From the above results, the silicon oxide film is brought to a level equivalent to that of the thermal oxide film by performing the plasma reforming process at a low processing pressure of 267 Pa or less and an O ₂ / Ar + O ₂ ratio of 0.23 or less. It has been shown that the film quality can be improved to a dense and high-quality film with few defects. It was also confirmed that the electrical characteristics of the device can be improved by using the silicon oxide film thus modified.

Next, it was examined how the amount of chlorine (derived from the raw material SiH ₂ Cl ₂ ) remaining in the silicon oxide film formed by the CVD method changes due to the plasma modification treatment. The amount of residual chlorine in the silicon oxide film was measured by TXRF (total reflection X-ray Fluorescence) analysis. The results are shown in Table 3.

Table 3 shows that when the plasma reforming process is performed, the amount of residual chlorine is smaller than when the reforming process is not performed, and impurities in the silicon oxide film can be removed. Note that a thermal annealing process may be performed after the plasma modification process. By combining the plasma reforming treatment with the thermal annealing treatment, the amount of residual chlorine could be reduced to 9.60 × 10 ¹¹ [atoms / cm ² ].

Next, using the plasma processing apparatus 100, the silicon substrate was subjected to plasma oxidation treatment under the conditions shown in Table 4 below (conditions 5 to 7) to form a silicon oxide film. The formed silicon oxide film is peeled off, and the state of the interface (SiO ₂ / Si interface) between the silicon oxide film and silicon of the silicon substrate is measured with an atomic force microscope (AFM) to calculate the flatness RMS. did. The results are shown in Table 4 and FIG. For reference, the RMS of the flatness was similarly calculated for the silicon oxide film obtained by thermally oxidizing the silicon substrate by the WVG method, and the results are shown in Table 4 and FIG.

From the results shown in Table 4 and FIG. 14, the RMS of the flatness is 0.13 nm or less in both conditions 5 and 6 in which the plasma oxidation processing is performed at a low processing pressure of 133 Pa or less using the plasma processing apparatus 100. It was confirmed that the state of the interface (SiO ₂ / Si interface) between the silicon oxide film and silicon can be formed extremely flat. On the other hand, in the silicon oxide film formed by thermal oxidation treatment or plasma oxidation treatment under a high pressure condition of 667 Pa, the RMS of flatness exceeds 0.2 nm, and the interface between the silicon oxide film and silicon The (SiO ₂ / Si interface) could not be flattened much.

  The RMS of the flatness changes greatly in the range of about 0.1 nm to 0.2 nm, and thus greatly affects the performance of devices that are highly integrated. In order to maintain good device performance, the RMS of flatness is preferably 0.13 nm or less, for example 0.05 to 0.13 nm or less. In the method for forming an insulating film in this embodiment, the flatness requirement can be satisfied by performing plasma oxidation using the plasma processing apparatus 100.

From the above results, in order to set the RMS of the flatness of the interface between the silicon oxide film and silicon (SiO ₂ / Si interface) to 0.13 nm or less, the processing pressure of the plasma oxidation treatment is 267 Pa or less, for example, 6.7 Pa or more and 267 Pa. It is preferable that the pressure be not more than 133 Pa, for example, 6.7 Pa to 133 Pa, more preferably 67 Pa or less, for example, 6.7 Pa to 67 Pa.

  Further, the oxygen partial pressure in the plasma oxidation treatment is preferably 5 Pa or less, for example, 0.1 Pa or more and 5 Pa or less, and more preferably 2 Pa or less, for example 0.1 Pa or more and 2 Pa or less.

  Further, it was found from the comparison between the condition 5 and the condition 6 that it is more preferable to add hydrogen to the process gas in the plasma oxidation process. In this case, the ratio of the hydrogen gas flow rate to the oxygen gas flow rate is preferably 25% or more, for example, 25% or more and 75% or less, and more preferably 50% or more and 75% or less.

  As described above, in the method for forming an insulating film of the present embodiment, the interface between silicon and a silicon oxide film as an insulating film is extremely flat compared to the flatness of a silicon substrate used for device manufacturing. A silicon oxide film is formed, an insulating film is formed thereon by a CVD method, and the insulating film is formed by plasma-modifying the insulating film. Therefore, for example, it is highly necessary to suppress the interface state density. In addition, the present invention can be preferably used for the above-described application (for example, forming a gate insulating film of a TFT element) that requires a dense and high-quality insulating film.

[Second Embodiment]
Next, a method for forming an insulating film according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 15 is a flowchart showing an example of the procedure of the insulating film forming method according to the second embodiment, and FIG. 16 is a diagram for explaining the main steps. In this embodiment mode, after the plasma oxidation treatment, the formation of the insulating film by the CVD method and the plasma modification treatment are repeated a plurality of times so that a dense and high-quality insulating film can be formed in a thick film.

  In FIG. 15, first, in step S <b> 11, the wafer W to be processed is loaded into the plasma processing apparatus 100 (process module 101 a) by the transfer apparatus 109 in the vacuum-side transfer chamber 103 according to the above procedure. Next, in step S12, a plasma oxidation process is performed on the silicon layer 201 exposed on the surface of the wafer W as shown in FIG. By this plasma oxidation treatment, as shown in FIG. 16B, silicon of the silicon layer 201 is oxidized from the surface to form a silicon oxide film 202 as a first insulating film with a predetermined thickness. The processes in steps S11 and S12 are the same as the processes in steps S1 to S2 (see FIG. 6) in the first embodiment, and thus detailed description thereof is omitted.

  Next, in step S13, the wafer W on which the silicon oxide film is formed is transferred to the single wafer CVD film forming apparatus 300 (process module 101b or 101c) by the transfer device 109 in the vacuum side transfer chamber 103. This transfer is performed in a vacuum state by the transfer device 109 in the vacuum side transfer chamber 103.

  Next, in step S14, as shown in FIG. 16C, a film forming process by a CVD method is performed on the silicon oxide film 202 formed on the surface of the wafer W. As a result, as shown in FIG. 16D, a silicon oxide film 203 as a second insulating film is formed on the silicon oxide film 202. As this CVD method, the CVD method is used in this embodiment using the substrate processing system 200, but it is possible to form a film by a method such as a thermal CVD method, a low pressure CVD method, or an atmospheric pressure CVD method.

Next, in step S15, the wafer W on which the silicon oxide film 202 and the silicon oxide film 203 are formed is transferred to a plasma processing apparatus 100 (process module 101d) as a plasma modification processing apparatus. This transfer is performed in a vacuum state by the transfer device 109 in the vacuum side transfer chamber 103. Next, in step S <b> 16, as shown in FIG. 16E, plasma modification processing is performed on the silicon oxide film 203. In the present embodiment, the processes in steps S13 to S16 are repeated a plurality of times as necessary. That is, as shown in FIGS. 16F and 16G, a silicon oxide film 204 as a second insulating film is further formed on the silicon oxide film 203 as the second insulating film by a CVD method. Then, as shown in FIG. 16 (h), the uppermost silicon oxide film 204 is subjected to plasma modification treatment as shown in FIG. Processing of step S13~ step S16, the total thickness _{T 3} of the second insulating film (a silicon oxide film 203, 204 ...) are repeatedly performed until the predetermined thickness. In addition, since the process of step S13-step S16 can be performed similarly to the process (refer FIG. 6) of step S3-step S6 of 1st Embodiment, detailed description is abbreviate | omitted here.

  As described above, after repeating the processing from step S13 to step S16, the wafer W processed by the transfer device 109 in the vacuum transfer chamber 103 is unloaded from the plasma processing apparatus 100 (process module 101d) in step S17. The wafer is stored in the wafer cassette CR of the load port LP in the above procedure.

In the method of forming the insulating film of the present embodiment, by repeating the steps S13~ step S16, the thickness T ₃ of the dense high-quality insulating film (silicon oxide film) can be formed to a desired thickness. That is, even if a thick silicon oxide film having a thickness of 10 nm to 1000 nm can be formed by a single CVD method, it is difficult to improve the film quality to a dense and high quality as it is. The reason for this is that, as described above, O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals have a low ability to permeate the silicon oxide film that is the object of the modification treatment, and therefore, a silicon oxide film that can be plasma-modified. This is because the thickness (depth from the surface) is limited. Therefore, in the method for forming the insulating film of the present embodiment, the deposition of the silicon oxide film by the CVD method as the insulating film, by repeatedly performing the plasma modification treatment, with the desired thickness T _3, a dense A high quality insulating film can be formed.

  In addition, by performing plasma oxidation treatment on the underlying silicon layer in step S12 prior to film formation by a plurality of CVD methods, the interface between the silicon and the silicon oxide film can be planarized. Accordingly, an increase in interface state density due to accumulation of fixed charges can be prevented, carrier mobility can be secured, and electrical characteristics of the device can be improved.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment. In the process modules 101a and 101d, both the plasma oxidation process in step S12 and the plasma modification process in step S16 may be performed.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the silicon oxide film (SiO film ₂ ) formed by the thermal CVD method is used as the insulating film to be subjected to the plasma reforming process. However, the insulating film is not limited to the silicon oxide film formed by the thermal CVD method. It is possible to target a silicon oxide film formed by a CVD method such as a plasma CVD method. In this case, a higher reforming effect can be obtained for a silicon oxide film having a poor film quality (for example, a poor film quality).

  Further, the insulating film to be subjected to the plasma reforming treatment is not limited to the silicon oxide film, but a high dielectric constant metal oxide film containing an oxide of metal such as zirconium, tantalum, titanium, barium, strontium, aluminum, hafnium, etc. The plasma modification process can also be applied to the (Hi-k film). In this case, since a flat interface cannot be formed only by forming a high dielectric constant metal oxide film on the silicon surface by CVD, plasma oxidation is performed before film formation to form an extremely flat interface. It is effective to form a high dielectric constant metal oxide film thereon.

It is a top view which shows schematic structure of a substrate processing system. It is a schematic sectional drawing which shows an example of the plasma processing apparatus suitable for implementation of the formation method of the insulating film of this invention. It is drawing which shows the structure of a planar antenna. It is explanatory drawing which shows the structure of a control part. It is a schematic sectional drawing which shows an example of the single wafer CVD film-forming processing apparatus suitable for implementation of the formation method of the insulating film of this invention. It is explanatory drawing which shows the outline of the procedure of the formation method of the insulating film which concerns on the 1st Embodiment of this invention. It is explanatory drawing explaining the main processes of the formation method of the insulating film which concerns on the 1st Embodiment of this invention. The mechanism of flattening of the Si / SiO ₂ interface in the plasma oxidation process is a diagram illustrating schematically. It is explanatory drawing which illustrates typically the modification | reformation mechanism in a plasma modification process. It is sectional drawing which shows schematic structure of the TFT element which can apply the formation method of the insulating film which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the pressure of a plasma modification process, and the leakage current characteristic of a MOS capacitor. It is a graph which shows the relationship between the pressure of a plasma modification process, and the TDDB characteristic of a MOS capacitor. Is a graph showing the relationship between the _{O 2 / (Ar + O 2} ) ratio and TDDB in plasma modification process. Is a graph showing the results of the flatness RMS of SiO 2 / _Si interface as measured by atomic force microscopy. It is explanatory drawing which shows the outline of the procedure of the formation method of the insulating film which concerns on the 2nd Embodiment of this invention. It is explanatory drawing explaining the main processes of the formation method of the insulating film which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Chamber (processing chamber), 2 ... Mounting stand, 3 ... Support member, 5 ... Heater, 12 ... Exhaust pipe, 15 ... Gas introduction part, 16 ... Carry-in / out port, 18 ... Gas supply mechanism, 19a ... Inert gas supply 19b ... oxygen-containing gas supply source, 19c ... hydrogen gas supply source, 24 ... exhaust device, 28 ... transmission plate, 29 ... sealing member, 31 ... planar antenna, 32 ... microwave radiation hole, 37 ... waveguide, 37 ... Coaxial waveguide, 37b ... Rectangular waveguide, 39 ... Microwave generator, 50 ... Control unit, 51 ... Process controller, 52 ... User interface, 53 ... Storage unit, 100 ... Plasma processing device, 200 ... Substrate Processing system, 300 ... Single wafer CVD film forming apparatus, W ... Semiconductor wafer (substrate)

Claims (15)

A plasma oxidation process for forming a silicon oxide film as a first insulating film by plasma oxidizing the silicon exposed on the surface of the object to be processed with plasma of a processing gas containing a rare gas and an oxygen gas;
A CVD step of forming a second insulating film on the silicon oxide film by a CVD method;
A plasma reforming process for performing a reforming process on the second insulating film using plasma of a processing gas containing a rare gas and an oxygen gas;
With
In the plasma oxidation processing step, in a plasma processing apparatus that introduces microwaves into a processing chamber using a planar antenna having a plurality of holes, the processing pressure is in a range of 6.7 Pa to 267 Pa and the total flow rate of the processing gas The flow rate ratio of the oxygen gas is within a range of 0.1% to 30%, and the active species in the plasma are O ₂ ⁺ ions and O ( ¹ D ₂ ) as compared with O ( ³ P ₂ ) radicals. Using a plasma with a relatively high concentration of radicals ,
In the plasma reforming process, in the plasma processing apparatus in which microwaves are introduced into the processing chamber by a planar antenna having a plurality of holes, the processing pressure is within a range of 6.7 Pa to 67 Pa and the total flow rate of the processing gas is The oxygen gas flow rate ratio is in the range of 0.1% to 30% and the microwave power density is in the range of 0.51 W / cm ^{2 to} 2.56 W / cm ² , as the active ^{species, O} (3 _{P 2)} than in the _{radical, O} ^{2 +} ions and ^O (1 _{D 2)} forming method of the insulating film in which the concentration of the radical and wherein Rukoto with relatively high plasma.   The first insulating film formed by the plasma oxidation treatment step has a flatness RMS of an interface with the silicon in a range of 0.05 to 0.13 nm and a thickness in a range of 3 to 10 nm. The method for forming an insulating film according to claim 1, wherein:   3. The method of forming an insulating film according to claim 1, wherein the second insulating film formed by the CVD process has a thickness in a range of 3 to 10 nm.   The flow rate ratio of the oxygen gas with respect to the total flow rate of the processing gas in the plasma oxidation treatment step is in a range of 0.5% to 3%, according to any one of claims 1 to 3. Of forming an insulating film.   The flow rate ratio of the oxygen gas with respect to the total flow rate of the processing gas in the plasma reforming treatment step is in a range of 0.1% to 5%, according to any one of claims 1 to 4. The insulating film formation method as described.   6. The method for forming an insulating film according to claim 1, wherein the processing pressure in the plasma oxidation processing step is in a range of 6.7 Pa to 67 Pa. 7. Wherein the second insulating film, insulating film forming method according to any one of claims 1 to claim 6, characterized in that formed by a plasma CVD method or a thermal CVD method. 2. The CVD process and the plasma reforming process are repeated a plurality of times until the total thickness of the second insulating film reaches a predetermined thickness determined in advance. The method for forming an insulating film according to claim 7 . Insulating film as claimed in any one of claims 8, wherein the plasma oxidation treatment step and the treatment temperature in the plasma modification treatment step, characterized in that it is in the range of 200 ° C. or higher 600 ° C. or less Forming method. Method of forming a dielectric film according to any one of claims 1 to claim 9, characterized in that the plasma oxidation process and the plasma modification process in the same chamber. Said second insulating film, claim 1, characterized in that a silicon oxide film which is deposited by CVD method using dichlorosilane and N _{2 O} as material gases according to any one of claims 10 A method for forming an insulating film.   12. The plasma oxidation treatment step according to claim 1, wherein the processing gas contains hydrogen, and a flow rate ratio of the hydrogen gas to a flow rate of the oxygen gas is in a range of 25% to 75%. 2. A method for forming an insulating film according to item 1. A computer-readable storage medium storing a control program that runs on a computer,
In the processing system having a plurality of processing chambers for performing predetermined processing on the object to be processed at the time of execution, the control program converts the silicon exposed on the surface of the object to be processed into a processing gas containing a rare gas and an oxygen gas. A plasma oxidation process for forming a silicon oxide film as a first insulating film by performing a plasma oxidation process using a plasma; a CVD process for forming a second insulating film on the silicon oxide film by a CVD method; And a plasma reforming process for performing a reforming process on the second insulating film using a plasma of a processing gas containing a rare gas and an oxygen gas. Controlling the processing system;
In the plasma oxidation processing step, in a plasma processing apparatus that introduces microwaves into a processing chamber using a planar antenna having a plurality of holes, the processing pressure is in a range of 6.7 Pa to 267 Pa and the total flow rate of the processing gas The flow rate ratio of the oxygen gas is within a range of 0.1% to 30%, and the active species in the plasma are O ₂ ⁺ ions and O ( ¹ D ₂ ) as compared with O ( ³ P ₂ ) radicals. Using a plasma with a relatively high concentration of radicals ,
In the plasma reforming process, in the plasma processing apparatus in which microwaves are introduced into the processing chamber by a planar antenna having a plurality of holes, the processing pressure is within a range of 6.7 Pa to 67 Pa and the total flow rate of the processing gas is The oxygen gas flow rate ratio is in the range of 0.1% to 30% and the microwave power density is in the range of 0.51 W / cm ^{2 to} 2.56 W / cm ² , Computer reading characterized in that the active species is a plasma having a relatively high concentration of O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals compared to O ( ³ P ₂ ) radicals. Possible storage medium. A first processing chamber that performs a first process on a target object, a second processing chamber that performs a second process different from the first process on the target object, and a target object And a third processing chamber for performing a third process different from the second process,
In the first processing chamber, as the first processing, the silicon exposed on the surface of the object to be processed is subjected to plasma oxidation treatment with plasma of a processing gas containing a rare gas and oxygen gas to oxidize the first insulating film. A silicon film is formed, and then in the second processing chamber, a second insulating film is formed on the silicon oxide film by the CVD method as the second processing, and then in the third processing chamber. A control unit for controlling each processing chamber so as to perform a plasma reforming process using plasma of a processing gas containing a rare gas and an oxygen gas for the second insulating film as the third processing, control unit further wherein the plasma oxidation treatment, a plurality of the plasma processing apparatus for introducing a microwave into the processing chamber by a planar antenna having a hole, the processing pressure is more than 6.7 Pa 267 Pa following range An inner, and the flow ratio of the oxygen gas to the total flow rate of the processing gas is performed in the range of 30% 0.1% plasma used is, as the active species in the plasma, O ( ³ P ₂ ) radicals compared to the radicals, and the concentration of O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals is controlled to be relatively high ,
In the plasma processing apparatus in which the plasma reforming process introduces microwaves into the processing chamber using a planar antenna having a plurality of holes, the processing pressure is in a range of 6.7 Pa to 67 Pa, and the total flow rate of the processing gas is the flow ratio of oxygen gas is in the range of 30% 0.1% and the power density of the microwave is performed in the range of 0.51W / cm ² or more 2.56 W / cm ² or less, The plasma to be used is controlled so that the active species in the plasma is a plasma having a relatively high concentration of O ₂ ⁺ ions and O ( ¹ D ₂ ) radicals as compared to O ( ³ P ₂ ) radicals. A processing system characterized by The processing system according to claim 14, wherein the first processing chamber and the third processing chamber are the same processing chamber.

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