JP2009021442A - Method of forming film for porous membrane and computer-readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a porous low dielectric constant membrane with stability and with good repeatability by a plasma CVD process using organic silicon compound materials. <P>SOLUTION: Oxygen plasma treatment of a surface of a SiOCH film formed by a plasma CVD process using organic silicon compound materials is carried out to form a surface densification layer. In addition, by hydrogen plasma treatment, a CHx group and an OH group are emitted from the SiOCH film under the surface densification layer via the surface densification layer at a controlled rate to form a porous low dielectric constant membrane with stability. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally relates to a method for forming a dielectric film, and more particularly to a method for forming a SiOCH film.

  In recent miniaturized semiconductor devices, a so-called multilayer wiring structure is used to electrically connect a huge number of semiconductor elements formed on a substrate. In the multilayer wiring structure, a large number of interlayer insulating films in which wiring patterns are embedded are stacked, and a wiring pattern of one layer is formed in a wiring pattern of an adjacent layer or a diffusion region in a substrate and the interlayer insulating film. They are interconnected via contact holes.

  In such a miniaturized semiconductor device, complicated wiring patterns are formed close to each other in the interlayer insulating film, so that the wiring delay (RC delay) of the electric signal due to the parasitic capacitance in the interlayer insulating film becomes a serious problem. . That is, it is important to reduce the product of the wiring resistance R and the wiring capacitance C as a wiring technology for high speed and low power consumption.

For this reason, in recent ultra-miniaturized semiconductor devices called so-called sub-micron or sub-quarter micron, a conventional silicon oxide film (SiO ₂ film) having a relative dielectric constant of about 4 is used as an interlayer insulating film constituting a multilayer wiring structure. ), An F-added silicon oxide film (SiOF film) having a relative dielectric constant of about 3 to 3.5 is used.

However, there is a limit to the reduction of the dielectric constant in the SiOF film. In such an SiO ₂ -based insulating film, the dielectric constant of less than 3.0 required for the semiconductor device of the generation after the design rule of 0.1 μm. The rate was difficult to achieve.

  On the other hand, there are various materials for the so-called low dielectric constant (low-K) insulating film having a lower relative dielectric constant, but the interlayer dielectric used for the multilayer wiring structure not only has a low relative dielectric constant, It is necessary to use materials with high mechanical strength and stability against heat treatment.

The SiOCH film is a next-generation ultrahigh-speed semiconductor in that it has sufficient mechanical strength and can achieve a relative dielectric constant of 2.5 or less, and can be formed by a CVD method that is convenient for the manufacturing process of semiconductor devices. It is promising as a low dielectric constant interlayer insulating film used in devices.
WO2005 / 045916 JP 2005-093721 A JP 2004-158793 A JP 2004-158794 A JP 2005-017085 A JP 2005-093721 A JP 2005-175085 A JP 2005-026468 A WO2003 / 019645 Japanese translation of PCT publication No. 2003-503849 Special table 2002-538604 gazette JP 2004-200626 A JP-A-8-236520 WO2001 / 097296 publication JP 2004-158793 A WO2001 / 097269 JP 2004-200626 A Japanese translation of PCT publication No. 2003-503849 Special table 2002-538604 gazette JP 2002-110636 A JP 7-106299 A Japanese Patent Laid-Open No. 6-84888 Patent Publication No. 2506539 A. Grill and DA Neumayer, J. Appl. Phys. Vol. 94, No. 10, Nov. 15, 2003

  Conventionally, it has been reported that the SiOCH film can be formed by a parallel plate type plasma processing apparatus. However, the SiOCH film formed by the normal CVD process has a relative dielectric constant between 3 and 4, and is around 2.2, which is achieved by coating type insulating films such as organic SOG and SiLK (registered trademark). The relative dielectric constant has not been reached.

  In the SiOCH film, as one means for achieving a relative dielectric constant comparable to such a coating type insulating film, it can be considered that the film is a porous film. For example, in Patent Document 9, a SiOCH film deposited by a CVD method is exposed to hydrogen radicals excited by microwave plasma, and CHx groups and OH groups are discharged out of the film from the SiOCH film deposited on the substrate. Describes the technology to obtain

  However, in the method of reforming the SiOCH film formed on the substrate by performing hydrogen plasma treatment as described above, delicate control is required for the reforming process, and the reforming process is executed stably in the mass production process. It was difficult.

That is, in the above prior art, plasma-excited hydrogen radicals break Si—CHx bonds or Si—OH bonds in the film, and the broken CHx groups and OH groups are in the form of methane (CH ₄ ) molecules outside the film. However, when the reforming process is performed under optimum conditions, the methane molecules thus formed act to expand the SiOCH film, and as a result, spaces in the film, that is, vacancies are formed. As a result, the relative dielectric constant of the SiOCH film decreases.

  However, in this conventional reforming process, when the reforming process conditions are outside the narrow optimum range, the SiOCH film shrinks instead of expanding, and the relative dielectric constant of the film is rather increased due to the increase in density accompanying the shrinking. It will increase.

  According to one aspect, the present invention provides a step of forming a dielectric film containing an organic functional group and a hydroxyl group on a substrate using an organic silicon compound raw material, and a dense layer for removing the organic functional group on the surface of the dielectric film. Forming a surface densified layer on the surface of the dielectric film, exposing the dielectric film formed with the surface densified layer to plasma-excited hydrogen radicals, and And a step of forming pores in the dielectric film body by removing hydroxyl groups, and providing a method for forming a porous film.

  According to another aspect, the present invention provides a computer-readable recording medium having recorded thereon a program for causing a substrate processing system to be controlled by a general-purpose computer and causing the substrate processing system to execute a porous film forming process on a silicon substrate. The substrate processing system is formed by combining a first substrate processing apparatus and a second substrate processing apparatus, and in forming the porous film, the substrate to be processed is the first substrate processing apparatus. In the first substrate processing apparatus, in the first substrate processing apparatus, in the first substrate processing apparatus, a step of forming a dielectric film containing an organic functional group and a hydroxyl group from the organic silicon compound raw material on the substrate; Performing a densification treatment to remove the organic functional group on the surface of the dielectric film, and forming a surface densification layer on the surface of the dielectric film; and the substrate to be processed on which the densification treatment has been performed. In the second substrate processing apparatus, and in the second substrate processing apparatus, the dielectric film formed with the surface densified layer is exposed to plasma-excited hydrogen radicals, and the organic functional group is exposed. Forming a hole in the dielectric film body by removing a group, and providing a computer-readable recording medium.

According to the present invention, the porous film is formed by forming a dielectric film containing an organic functional group and a hydroxyl group on the substrate by using an organic silicon compound raw material, and the organic functional group and the hydroxyl group are formed on the surface of the dielectric film. A surface densification layer having a higher density than the dielectric film body is formed on the surface of the dielectric film, and the dielectric film on which the surface densification layer is formed is plasma-excited. In the hole forming step, by performing the step of forming holes in the dielectric film main body by removing the organic functional groups and hydroxyl groups by exposing to the generated hydrogen radicals. , Organic functional groups such as CH ₃ , C ₂ H ₅ ,... Generally abbreviated as CHx, and hydroxyl groups (OH) are discharged out of the film at a controlled rate, Effective shrinkage of dielectric film It is possible to win to become. As a result, an increase in the density of the dielectric film is suppressed, and a porous film having a low dielectric constant can be obtained.

  Further, after the film formation process, only the film formation source gas is shut off, and the supply of plasma gas and oxidizing gas and the supply of plasma power are continued, thereby effectively suppressing the generation of particles at the end of the film formation process. As a result, the yield of film formation is greatly improved.

[First Embodiment]
FIG. 1 shows the configuration of a parallel plate type substrate processing apparatus 11 used for forming a dielectric film in the present invention.

  Referring to FIG. 1, a substrate processing apparatus 11 includes a processing container 12 made of a conductive material such as anodized aluminum and exhausted by an exhaust apparatus 14 such as a turbo molecular pump through an exhaust port 13. Inside the processing container 12, a susceptor 17 that holds the substrate W to be processed is supported by a substantially cylindrical susceptor support 16. The susceptor 17 also functions as a lower electrode of the parallel plate type substrate processing apparatus 11, and an insulator 18 such as ceramic is provided between the susceptor support 16 and the susceptor 17. The processing container 12 is grounded.

  A refrigerant flow path 19 is provided inside the susceptor support base 16, and by circulating the refrigerant in the refrigerant flow path 19, the susceptor 17 and the substrate W to be processed thereon are subjected to a substrate processing process. It is controlled to a desired substrate temperature.

  Further, a gate valve 15 is provided on the side wall of the processing container 12, and the substrate W to be processed is carried into and out of the processing container 12 with the gate valve 15 opened.

  The exhaust device is further connected to an abatement device 36, and the exclusion device 36 renders the exhaust gas discharged from the processing container 12 discharged by the exhaust device 14 harmless. For example, the abatement device 36 may be a device that converts atmospheric gas into a harmless substance by burning or pyrolyzing the atmosphere gas with a predetermined catalyst.

  The susceptor support 16 is provided with lift pins 20 for transferring the semiconductor substrate W to be moved up and down by an elevating mechanism (not shown). The susceptor 17 has a concave disk-shaped portion formed at the center of the upper surface thereof, and an electrostatic chuck (not shown) having a shape corresponding to the substrate to be processed W is provided on the concave disk-shaped portion. The substrate W to be processed placed on the susceptor 17 is electrostatically attracted to the electrostatic chuck when a DC voltage is applied.

  Further, a shower head 23 is provided above the susceptor 17 so as to face the substrate W to be processed on the susceptor 17 so as to be substantially parallel to the susceptor 17.

  The surface of the shower head 23 facing the susceptor 17 has a number of gas supply holes 24 and is provided with an electrode plate 25 made of aluminum or the like. The shower head 23 is connected to the treatment by an electrode support 26. The container 12 is supported on the ceiling portion. Another coolant channel 27 is formed inside the shower head 23, and the coolant is circulated through the coolant channel 27 to maintain the shower head 23 at a desired temperature during the substrate processing process. Is done.

Further, a gas introduction pipe 28 is connected to the shower head 23, while the gas introduction pipe 28 comprises a raw material container 29 holding trimethylsilane ((CH ₃ ) ₃ SiH) raw material and an oxidant holding oxygen gas. The gas source 30 is connected to an Ar gas source 31 holding argon (Ar) gas via respective mass flow controllers and valves (not shown).

  The source gas and the processing gas from the gas sources 29 to 31 are mixed in a hollow portion (not shown) formed in the shower head 23 via the gas introduction pipe 28, and the gas supply holes of the shower head 23 are mixed. 24 to the process space near the surface of the substrate W to be processed.

  The shower head 23 is further connected with a second high-frequency power source 32 via a second matching unit 33. The high-frequency power source 32 has a frequency of 450 kHz to 300 MHz, preferably 13.56 to 150 MHz. A range of high frequency power is supplied to the showerhead 23. By supplying such high frequency high frequency power, the shower head 23 functions as an upper electrode, and plasma is formed in the processing vessel 12. As the plasma source, a microwave method and an ICP method are also applicable.

  Further, the substrate processing apparatus 11 of FIG. 1 includes a control unit 34 that controls the operation of the entire processing apparatus 11 including a film forming process on the substrate W to be processed. The control unit 34 includes a microcomputer control device including an MPU (Micro Processing Unit), a memory, and the like, and stores a program for controlling each part of the device according to a predetermined processing sequence in the memory. Control.

  2A to 2C show an outline of a film forming method according to the first embodiment of the present invention.

  Referring to FIG. 2 (A), a silicon substrate 41 is introduced into the substrate processing apparatus 11 of FIG. 1, and the substrate temperature is from 13.3 to 13333 Pa, preferably from 100 to 1000 Pa at room temperature to 200 ° C. Ar gas at a flow rate of 100 to 6000 SCCM, preferably 100 to 1000 SCCM, oxygen gas at 50 to 2000 SCCM, preferably 50 to 200 SCCM, organosilicon compound gas such as trimethylsilane (3MS) at a flow rate of 50 to 2000 SCCM, preferably 50 to 200 SCCM The silicon substrate 41 is supplied into the processing container 12 and further supplied with a high frequency of 13 to 150 MHz from the high frequency source 32 to the shower head 23 with a power of 50 to 3000 W, preferably 100 to 750 W. Si and oxygen on the surface of And Do constituent elements, to which contained carbon and hydrogen, the so-called SiOCH film 42, 100 to 1000 nm at 500-2000 nm / min deposition rate, preferably a film thickness of 200 to 400 nm, it is formed.

  For example, the SiOCH film is formed by supplying Ar gas at 600 SCCM, oxygen gas at 100 SCCM, and trimethylsilane gas at 100 SCCM into the processing vessel 12 at a substrate temperature of 45 ° C. under a pressure of 300 Pa, and the shower head. 23 is supplied with a high frequency of 13.56 MHz with a power of 500 W, and the SiOCH film 42 can be formed to a thickness of about 400 nm at a deposition rate of 1500 nm / min. However, in the substrate processing apparatus 11, the distance between the shower head 23 and the susceptor 17 is set to 25 mm. A wider gap can reduce plasma damage and improve uniformity. The interval is preferably in the range of 10 to 500 mm.

  The SiOCH film thus formed has a relatively high relative dielectric constant of about 3-4.

Next, in this embodiment, in the process of FIG. 2B, the supply of the trimethylsilane gas is shut off in the same parallel plate type substrate processing apparatus 11 with respect to the structure of FIG. And the surface of the SiOCH film 42 is plasma-treated at a substrate temperature from room temperature to 200 ° C., preferably at the same substrate temperature as when the SiOCH film 42 is formed. , by replacing the CHx group and OH group such as CH ₃ or C ₂ H ₅ of the surface by oxygen, 5 to 20 nm from the surface, preferably with a thickness of 10 to 15 nm, high oxygen concentration, the SiO ₂ A densified layer 43 having a close composition is formed. Note that the modification step in FIG. 2B may be performed using oxygen radicals formed by surface reflection plasma, magnetron plasma, or microwave plasma described with reference to FIG. The damage to the SiOCH film 42 is reduced by executing the modification process of FIG. The proportion of the densified layer is preferably 0.5 to 20%, particularly 2.5 to 7.5% of the thickness of the SiOCH film 42.

  The step of FIG. 2B is performed, for example, for 10 to 300 seconds, preferably for 10 to 60 seconds. Thereafter, in this embodiment, in the step of FIG. 2C, the substrate on which the densified layer of FIG. 2B is formed is introduced into the microwave plasma processing apparatus shown in FIGS. The formed hydrogen radicals modify the SiOCH film under the densified layer 43 to form pores in the film, thereby forming a porous film 42A having a SiOCH composition.

  Referring to FIG. 3, the plasma processing apparatus 50 includes a processing container 51 in which a process space 51A is formed. In the processing container 51, a substrate holding table 52 for holding a substrate W to be processed is provided in the process space 51A. Is provided. The processing vessel 51 is evacuated by the APC 51D and the evacuation device 11E through a space 51B formed so as to surround the substrate holder 52 at the exhaust port 51C.

  The substrate holder 52 is provided with a heater 52A, and the heater 52A is driven by a power source 52C through a drive line 52B.

  Further, the processing container 51 is provided with a substrate loading / unloading port 51g and a gate valve 51G cooperating with the substrate loading / unloading port 51g, and the substrate W to be processed is loaded into the processing container 11 through the substrate loading / unloading port 51g. , Will be carried out again.

  An opening is formed on the processing container 51 corresponding to the substrate to be processed W, and the opening is closed by a top plate 53 made of a dielectric such as quartz glass. A gas ring 54 provided with a gas inlet and a number of gas inlets communicating therewith is provided below the top plate 53 so as to face the substrate W to be processed.

  Here, the top plate 53 functions as a microwave window, and a flat antenna 55 formed of a radial line slot antenna is provided on the top plate 53.

  In the illustrated example, a radial line slot antenna is used as the microwave antenna 55. Therefore, the antenna 55 has a planar antenna plate 55B disposed on the top plate 53, and a dielectric such as quartz so as to cover the planar antenna 55B. A slow wave plate 55A made of a body is arranged. The conductive cover 55D is configured to cover the slow wave plate 55A. A cooling jacket is formed on the cover 55D, and the top plate 53, the flat antenna plate 55B, and the slow wave plate 55A are cooled to prevent thermal damage and generate stable plasma.

  The planar antenna plate 55B is formed with a number of slots 55a and 55b described with reference to FIG. 4, and a coaxial waveguide 56 composed of an outer conductor 56A and an inner conductor 56B is connected to the center of the antenna 55, An internal conductor 56B passes through the slow wave plate 55A and is connected to and coupled to the center of the planar antenna 55B.

  The coaxial waveguide 56 is connected to a waveguide 110B having a rectangular cross section via a mode conversion unit 110A, and the waveguide 110B is coupled to a microwave source 112 via an impedance matching unit 111. Therefore, the microwave formed by the microwave source 112 is supplied to the planar antenna 55B via the rectangular waveguide 110B and the coaxial waveguide 56.

  FIG. 4 shows the configuration of the radial line slot antenna 55 in detail. However, FIG. 4 is a front view of the planar antenna plate 55B.

  Referring to FIG. 4, it can be seen that the planar antenna plate 55B has a number of slots 55a formed concentrically and in an orientation (T-shaped or C-shaped) so that adjacent slots are orthogonal to each other. .

  Therefore, when the microwave is supplied to the radial line slot antenna 55B from the coaxial waveguide 56, the microwave propagates while spreading in the radial direction in the antenna 55B, and at that time, the wavelength is transmitted by the slow wave plate 55A. Undergo compression. Therefore, the microwave is radiated as a circularly polarized wave from the slot 55a, generally in a direction substantially perpendicular to the planar antenna plate 55B.

  Further, as shown in FIG. 3, in the microwave plasma processing apparatus 50, a rare gas source 101A such as Ar, a hydrogen gas source 101H, and an oxygen gas source 101O are connected to the gas ring 54, the respective MFCs 103A, 103H, and 103O and the respective valves. 104A, 104H, 104O and the common valve 106 are connected. As described above, the gas ring 54 is formed with a large number of gas inlets so as to uniformly surround the substrate holding table 52. As a result, the Ar gas and the hydrogen gas are treated with the treatment gas. It is uniformly introduced into the process space 51A in the container.

  During operation, the process space 51A in the processing vessel 51 is set to a predetermined pressure by exhausting through the exhaust port 51C. In addition to Ar, a rare gas such as Kr, Xe, or Ne can be used.

Further, a microwave having a frequency of several GHz, for example, 2.45 GHz, is introduced into the process space 51A from the microwave source 112 via the antenna 115. As a result, a plasma density of 10 is formed on the surface of the substrate W to be processed. A high density plasma of ¹¹ to 10 ¹³ / cm ³ is excited.

  This plasma is characterized by an electron temperature as low as 0.5 to 2 eV. As a result, the plasma processing apparatus 50 performs processing without plasma damage on the substrate W to be processed. In addition, since radicals formed by plasma excitation flow along the surface of the substrate W to be processed and are quickly eliminated from the process space 51A, recombination of radicals is suppressed, which is very uniform and effective. Substrate processing is possible, for example, at 500 ° C. or lower.

Therefore, in the process of FIG. 2C, when the low electron temperature plasma is formed in the process space 51A and hydrogen gas is introduced into the low electron temperature plasma from the gas ring 54, the hydrogen gas is Plasma excitation generates hydrogen radicals H *. The formed hydrogen radical H * easily diffuses through the densified layer 43 and reaches the underlying SiOCH film 42, where it replaces CHx groups such as CH ₃ and C ₂ H ₅ or OH groups. The substituted CHx group or OH group is released as a gas through the densified layer 43. However, CHx groups and OH groups cannot freely pass through the densified layer 43 like hydrogen radicals, and are gradually released at a speed much slower than the passing speed of the hydrogen radicals. It is preferable to increase the exhaust speed.

  As a result, in the process of FIG. 2C, CHx groups and OH groups liberated in the SiOCH film 42 form an internal pressure, and these groups gradually pass through the densified layer 43 to the outside of the film. Even when released, there is no contraction of the film, such as a substantial increase in density in the film 42. Therefore, in the SiOCH film 42, atomic positions (sites) where the CHx groups or OH groups are eliminated and replaced with hydrogen form vacancies, and the SiOCH film 42 is formed by the process of FIG. 2C. Of these, the main body portion under the densified film 43 is changed to a porous film 42A. That is, the process of FIG. 2C is a hole forming process for forming holes in the SiOCH film.

  In one example, in the process of FIG. 2C, hydrogen gas and Ar gas are supplied at a flow rate of 200 SCCM and 1000 SCCM, respectively, at a substrate temperature of 400 ° C. and a pressure of 267 Pa, and a frequency of 2.45 GHz is supplied to the microwave antenna 55. This is performed by supplying a microwave of 360 kW with a power of 3 kW for 360 seconds. Here, the substrate temperature in the step of FIG. 2C is set to be 100 ° C. higher than the substrate temperature in the steps of FIGS. 2A and 2B, but not to exceed 400 ° C. . When the substrate temperature in FIG. 2C is set to 400 ° C. or higher, particularly in the manufacture of a large-scale semiconductor integrated circuit device or the like, in an ultrafine transistor or the like already formed on the substrate in the previous process. There arises a problem that the distribution profile of the impurity element is changed by the heat of the substrate processing. 2C is preferably executed at a process pressure in the range of 20 to 1333 Pa, particularly 20 to 650 Pa. At that time, it is preferable to use plasma power in the range of 500 W to 6 kW, particularly 500 W to 3 kW. Or it is preferable to carry out under a low plasma energy condition under a high pressure of 133.3 to 1333 Pa.

  In FIG. 5, data A to D correspond to an experiment performed under the conditions shown in FIG.

  Referring to FIG. 5, the oxidation process of FIG. 2B was omitted, and after the SiOCH film forming process of FIG. 2A, the process suddenly shifted to the vacancy forming process of FIG. 2C. In this case, the relative dielectric constant obtained is about 2.8 (process condition A), and the removal of the CHx group or OH group occurs rapidly during the hydrogen plasma treatment of FIG. It can be seen that the shrinkage does not cause satisfactory void formation and a decrease in the dielectric constant.

  In contrast, when the oxidation process of FIG. 2B is performed for 10 to 60 seconds, the value of the relative dielectric constant decreases with the oxidation process time. For example, when the oxidation process is performed for 60 seconds, the process condition B It can be seen that the relative dielectric constant is 2.55 at 2.5, 2.52 at process condition C, and 2.4 at process condition D. This relative permittivity is in a state including the densified layer 43, and when the densified layer 43 is removed after the step of FIG. 2C, the value of the relative permittivity further decreases. .

  Further, in the experiment (process condition E) under the same conditions as the process condition B in FIG. 6 except that the pressure during film formation is 400 Pa, even when the oxygen plasma treatment in FIG. A dielectric constant of .28 was confirmed to be achieved. In this way, the relative dielectric constant of the obtained SiOCH film can be controlled by controlling the pressure at the time of forming the SiOCH film, the oxygen plasma irradiation time after the film formation, and the hydrogen plasma irradiation time in the vacancy formation step. It is possible to further reduce the relative dielectric constant.

  That is, the pressure at the time of forming the SiOCH film 42 is set to 133.3 Pa or more, preferably 300 Pa or more, and then the oxygen plasma treatment and / or the hydrogen plasma treatment is performed, whereby the k value of the SiOCH film is set to 3. It can be reduced to less than 0. In addition, the k value can be reduced to 2.3 or less by setting the pressure during film formation to 400 Pa or more.

  FIG. 7 shows the FTIR spectrum of the ultra-low dielectric constant SiOCH film 42A obtained by the densification treatment step and hydrogen plasma treatment of FIG. 2C, in the state of only film formation (As-depo) in FIG. It shows in comparison with. However, FIG. 7 shows a state in which a densified layer 43 is formed on the SiOCH film 42A. In FIG. 7, each absorption peak is identified according to Non-Patent Document 1.

  Referring to FIG. 7, when the film subjected to the densification treatment and the hydrogen plasma treatment is compared with the As-depo film, the positions corresponding to the Si—O—Si cage structure are reduced while the methyl groups and OH groups are reduced. It can be seen that the absorption is increased in FIG. 5, which indicates that vacancies are actually formed in the SiOCH film 42A due to the elimination of the CHx group and the OH group. In addition, in the state of FIG. 2C, since the absorption corresponding to the Si—O—Si network is increased, it is considered that the mechanical strength is also increased.

  From FIG. 7, by performing the porous film forming step of FIG. 2 (C) after the surface densification step of FIG. 2 (B), pores are actually formed in the SiOCH film 42A, and the film 42A Is a porous membrane.

  FIG. 8 shows an outline of a cluster type substrate processing apparatus 60 that executes the processes of FIGS.

  Referring to FIG. 8, the cluster type substrate processing apparatus 60 is connected to a vacuum transfer chamber 601, a movable transfer arm 602 provided in the vacuum transfer chamber 601, and the vacuum transfer chamber 601. A processing chamber 200 in which the substrate processing apparatus 11 is stored, a processing chamber 300 in which the substrate processing apparatus 50 is connected to the vacuum transfer chamber 601, a load lock chamber 603 in which the substrate transfer apparatus 601 is connected, 604.

  Exhaust means (not shown) is connected to the processing chambers 200 and 300, the vacuum transfer chamber 601, and the load lock chambers 603 and 604.

  The processing chambers 200 and 300 and the load lock chambers 603 and 604 are connected to the vacuum transfer chamber 601 via openable and closable gate valves 601a to 601b, 601d and 601e, respectively, and the substrate to be processed is the gate valve described above. By opening any of these, the substrate is transferred from the vacuum transfer chamber 601 to any substrate processing chamber or from any substrate processing chamber to the vacuum transfer chamber 601.

  Further, the load lock chambers 603 and 604 are provided with gate valves 603a and 604a which can be opened and closed, respectively, and by opening the gate valve 603a, a wafer cassette containing a plurality of substrates to be processed in the load lock chamber 603. C1 is loaded. Similarly, by opening the gate valve 103b, the load lock chamber 604 is loaded with a wafer cassette C2 containing a plurality of substrates to be processed.

When performing substrate processing, for example, the substrate W ₀ to be processed is transferred from the cassette C 1 or C 2 to the processing chamber 200 by the transfer arm 602 via the vacuum transfer chamber 601, and the processing in the processing chamber 200 is performed. The completed substrate to be processed is transferred to the processing chamber 300 by the transfer arm 102 via the vacuum transfer chamber 601. The substrate W to be processed after the processing in the processing chamber 300 is stored in the cassette C1 in the load lock chamber 603 or the cassette C2 in the load lock chamber 604.

  FIG. 8 shows an example in which two processing chambers are coupled to the vacuum transfer chamber 601, but a processing container can be further connected to the surface 601A or 601B of the vacuum transfer device, for example, so that it can be used as a so-called multi-chamber system. It is. Accordingly, film formation, densification treatment, and hydrogen plasma treatment can be performed efficiently, and a low-density film can be formed with high throughput.

  In this case, the film formation and the densification process are executed by the same processing apparatus, and the hydrogen plasma process is executed by the processing apparatus of the department, or the film formation process, the densification process, and the hydrogen plasma process are performed by separate processing apparatuses. By executing this, overall throughput of the film forming process can be improved.

  FIG. 9 is a flowchart for explaining the overall operation of the cluster type substrate processing apparatus 60 of FIG.

  Referring to FIG. 9, in step 1, the substrate W to be processed is transferred to the processing chamber 200, the process corresponding to FIG. 2A is performed in the processing container 11, and the deposition of the SiOCH film 42 is performed. Done.

  Next, in step 2, only the supply of the organic silane source gas is shut off while maintaining the plasma in the same processing vessel 11 and continuing the supply of oxygen gas and Ar gas, and the process of FIG. Corresponding to the above, a surface densified layer 42A is formed on the surface of the SiOCH film 42.

  Next, in step 3, the substrate W to be processed is transferred from the processing chamber 200 to the processing chamber 300, and the hole forming step shown in FIG. 2C is performed by the substrate processing apparatus 50 shown in FIGS.

  The substrate processing apparatus 60 of FIG. 8 includes a control device 600A in order to control such a series of substrate processing processes. The step of forming the surface densified layer 42A in step 2 may be performed in the processing chamber 300. After the formation of the surface densified layer 42A in step 2, the temperature is increased for hydrogen plasma treatment. Since it is necessary, it is preferable to perform only the hydrogen plasma processing in another processing chamber 300.

  The control device 600A is actually a general-purpose computer, reads a storage medium recorded with program code means corresponding to the process of FIG. 7, and controls each part of the substrate processing apparatus 60 according to the program coating means.

In the present embodiment, the film forming process in FIG. 2A is not limited to the plasma CVD process, and can be performed by a coating process.

[Second Embodiment]
10A to 10D show an outline of a film forming method according to the second embodiment of the present invention. However, in the figure, the same reference numerals are given to the parts described above, and the description will be omitted.

  Referring to FIGS. 10A to 10D, FIGS. 10A to 10C are the same as FIGS. 2A to 2C, but in this embodiment, FIG. 10), the structure obtained in the step of FIG. 10C is further processed by plasma-excited oxygen radical O * or oxygen radical O * and hydrogen radical H *.

  For example, the structure obtained in the step of FIG. 10C is processed in the same microwave plasma processing apparatus with the same substrate temperature (for example, 400 ° C.) and the process pressure of approximately 20 to 1333 Pa, preferably 20 to 650 Pa. The pressure is set to a process pressure of, for example, 260 Pa, Ar gas is supplied at a flow rate of 250 SCCM, oxygen gas is supplied at a flow rate of 200 SCCM, and a microwave having a frequency of 2.45 GHz is supplied at a power of 500 W to 2 kW, for example, a power of 2 kW. As a result, the surface of the SiOCH film 42A is modified by oxygen radicals O *, and changes to the SiOCH film 42B. As a result of such a modification process, damage caused by the oxygen plasma process of FIG. 10B or the hydrogen plasma process of FIG. 10C on the surface of the SiOCH film 42A is eliminated or reduced.

  11A and 11B and FIGS. 12A and 12B show changes in leakage current characteristics of the SiOCH film due to such a modification process. However, FIGS. 11A and 11B show the relationship between the leakage current of the SiOCH film and the modification processing time for various oxygen gas / Ar gas flow ratios, and FIGS. 12A and 12B show the relationship between the leakage current and the modification processing time. The relationship is shown for various oxygen gas / hydrogen gas flow ratios.

  11A and 11B and FIGS. 12A and 12B, the film forming apparatus 11 of FIG. 1 is used as the SiOCH film, and the trimethylsilane is formed on a p-type silicon substrate at a temperature of 25 ° C. under a pressure of 100 Pa. Is used, and a film formed while supplying a high frequency of 27.12 MHz with a power of 250 W is supplied at a flow rate of 100 SCCM, oxygen gas at 100 SCCM, and Ar gas at a flow rate of 600 SCCM.

The leakage current value of the SiOCH film is desirably suppressed to 1 × 10 ⁻⁸ A / cm ² or less.

  FIG. 13 below shows details of an experiment in which the modification treatment of FIG. 10D was performed using only oxygen radicals.

  Referring to FIG. 13, in Experiment # 11, a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. 3 is applied to the SiOCH film obtained in the process of FIG. 10C (hereinafter referred to as the initial SiOCH film). Below, at a temperature of 400 ° C., Ar gas is supplied at a flow rate of 500 SCCM, hydrogen gas is supplied at a flow rate of 1000 SCCM, and a microwave having a frequency of 2.45 GHz is irradiated at a power of 2 kW for 120 seconds to perform hydrogen plasma treatment.

  In Experiment # 12, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas was supplied at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 2.45 GHz microwave at a power of 2 kW for 120 seconds, and subsequently, all gases and microwave power were shut off for 55 seconds, and then Ar at 400 ° C. under a pressure of 267 Pa. Gas plasma is supplied at a flow rate of 2000 SCCM, oxygen gas is supplied at a flow rate of 200 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 5 seconds to perform oxygen plasma treatment.

  In Experiment # 13, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas was supplied at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. 2. 45 GHz microwave is irradiated at a power of 2 kW for 120 seconds to perform hydrogen plasma treatment. Subsequently, all gases and microwave power are shut off for 55 seconds, and then Ar at 400 ° C. under a pressure of 400 Pa. Gas plasma is supplied at a flow rate of 2000 SCCM, oxygen gas is supplied at a flow rate of 200 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 5 seconds to perform oxygen plasma treatment.

  In Experiment # 14, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas was supplied at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 2.45 GHz microwave at a power of 2 kW for 120 seconds, and subsequently, all gases and microwave power were shut off for 55 seconds, and then Ar at 400 ° C. under a pressure of 267 Pa. Gas plasma is supplied at a flow rate of 2000 SCCM, oxygen gas is supplied at a flow rate of 5 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 20 seconds to perform oxygen plasma treatment.

  In Experiment # 15, the initial SiOCH film was supplied at a flow rate of 500 SCCM for Ar gas and 1000 SCCM for hydrogen gas at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 45 GHz microwave at a power of 2 kW for 120 seconds, followed by shutting off all gas and microwave power for 55 seconds, and then Ar gas at 400 ° C. under a pressure of 267 Pa. Is supplied at a flow rate of 2000 SCCM and oxygen gas at a flow rate of 200 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 20 seconds to perform oxygen plasma treatment.

  In Experiment # 16, the initial SiOCH film was supplied at a flow rate of 500 SCCM for Ar gas and 1000 SCCM for hydrogen gas at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 45 GHz microwave at a power of 2 kW for 120 seconds, followed by shutting off all gas and microwave power for 55 seconds, and then Ar gas at 400 ° C. under a pressure of 267 Pa. Is supplied at a flow rate of 2000 SCCM, oxygen gas is supplied at a flow rate of 5 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 40 seconds to perform oxygen plasma treatment.

  In Experiment # 17, the initial SiOCH film was supplied at a flow rate of 500 SCCM for Ar gas and 1000 SCCM for hydrogen gas at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 45 GHz microwave at a power of 2 kW for 120 seconds, followed by shutting off all gas and microwave power for 55 seconds, and then Ar gas at 400 ° C. under a pressure of 267 Pa. Is supplied at a flow rate of 2000 SCCM, oxygen gas at a flow rate of 200 SCCM, and a microwave with a frequency of 2.45 GHz is supplied at a power of 1.5 kW for 40 seconds to perform oxygen plasma treatment.

  FIG. 14 shows the details of an experiment in which the modification treatment of FIG. 10D shown in FIGS. 12A and 12B was performed with oxygen radicals and hydrogen radicals.

  Experiment # 1 is the same as Experiment # 11. The initial SiOCH film formed in the process of FIG. 10C is 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. At temperature, hydrogen plasma treatment is performed by supplying Ar gas at a flow rate of 500 SCCM and hydrogen gas at a flow rate of 1000 SCCM, and further irradiating a microwave with a frequency of 2.45 GHz at a power of 2 kW for 120 seconds.

  In Experiment # 2, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 2.45 GHz microwave at a power of 2 kW for 100 seconds, followed by addition of oxygen gas with a flow rate of 5 SCCM, and a plasma power of 1.5 kW. Hydrogen oxygen plasma treatment is performed for 2 seconds.

  In Experiment # 3, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas was supplied at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment was performed by irradiating a 2.45 GHz microwave at a power of 2 kW for 60 seconds, followed by addition of oxygen gas with a flow rate of 5 SCCM, and a plasma power of 1.5 kW. Hydrogen oxygen plasma treatment is performed for 2 seconds.

  In Experiment # 4, Ar gas was 500 SCCM, hydrogen gas was 1000 SCCM, and oxygen gas was 5 SCCM at a flow rate of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. 3 with respect to the initial SiOCH film. A hydrogen-oxygen plasma treatment is performed by irradiating a microwave having a frequency of 2.45 GHz with a power of 2 kW for 120 seconds.

  In Experiment # 5, Ar gas was supplied at a flow rate of 500 SCCM and hydrogen gas was supplied at a flow rate of 1000 SCCM at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. A hydrogen plasma treatment is performed by irradiating a 2.45 GHz microwave at a power of 2 kW for 100 seconds, followed by addition of oxygen gas with a flow rate of 25 SCCM and a plasma power of 1.5 kW. Hydrogen oxygen plasma treatment is performed for 2 seconds.

  In Experiment # 6, the initial SiOCH film was supplied at a flow rate of 500 SCCM for Ar gas and 1000 SCCM for hydrogen gas at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. .45 GHz microwave irradiation at a power of 2 kW for 60 seconds, followed by hydrogen plasma treatment, followed by addition of oxygen gas with a flow rate of 25 SCCM and a plasma power of 1.5 kW for 60 seconds under the same conditions. Hydrogen oxygen plasma treatment is performed.

  Further, in Experiment # 7 (not shown), Ar gas is 500 SCCM, hydrogen gas is 1000 SCCM, oxygen gas at a temperature of 400 ° C. under a pressure of 267 Pa in the substrate processing apparatus 50 of FIG. 3 with respect to the initial SiOCH film. Is supplied at a flow rate of 25 SCCM, and a microwave with a frequency of 2.45 GHz is irradiated at a power of 2 kW for 120 seconds to perform a hydrogen-oxygen plasma treatment.

  In all the experiments of FIGS. 13 and 14, the gap length of the plasma processing apparatus 50 is set to 55 mm.

Referring to FIGS. 11A and 11B, or FIGS. 12A and 12B, by performing such post-treatment with hydrogen radicals and oxygen radicals, or post-treatment with only oxygen radicals, the dielectric constant of the formed SiOCH film is low. While maintaining the rate, the leakage current characteristics can be improved as compared with the case where the reforming process is terminated at the stage of FIG. 10C, and the leakage current density is 1 × 10 ⁻⁸ A / cm ² or less. It can be seen that can be realized.

More specifically, in Experiment # 1 in which only hydrogen radical treatment was performed for 120 seconds and oxygen radical treatment was not performed, the average relative dielectric constant was 3.79 and the leakage current was 1.58 × 10 ⁻⁸ A / cm ^2. In contrast, in Experiment # 2, in which hydrogen radical treatment for 100 seconds was followed by treatment with hydrogen radicals and oxygen radicals for 20 seconds at an oxygen gas flow rate of 5 SCCM, the average relative dielectric constant was 3.64 and leakage was observed. In experiment # 3, where the current was 1.29 × 10 ⁻⁸ A / cm ² ; treatment with hydrogen radicals for 60 seconds, followed by treatment with hydrogen radicals and oxygen radicals for 60 seconds at an oxygen gas flow rate of 5 SCCM, the average ratio a dielectric constant of 3.29, leakage current 7.82 × 10 ^-9 a / cm ² next; 120 seconds at an oxygen gas flow rate 5SCCM from the beginning, treatment with hydrogen radicals and oxygen radicals In experiments conducted # 4, the average relative dielectric constant 3.36, leakage current 3.53 × 10 ^-9 A / cm ² next; After hydrogen radical treatment for 100 seconds, 20 seconds at an oxygen gas flow rate of 25SCCM In Experiment # 5, where treatment with hydrogen radicals and oxygen radicals was performed, the average relative dielectric constant was 3.34 and the leakage current was 8.55 × 10 ⁻⁹ A / cm ² ; after the hydrogen radical treatment for 60 seconds In Experiment # 6, in which treatment with hydrogen radicals and oxygen radicals was performed for 60 seconds at an oxygen gas flow rate of 25 SCCM, the average relative dielectric constant was 3.24 and the leakage current was 6.98 × 10 ⁻⁹ A / cm ² . It has become.

Experiment # 11, in which only hydrogen radical treatment was performed for 120 seconds and oxygen radical treatment was not performed, is the same as Experiment # 1, with an average relative dielectric constant of 3.79 and a leakage current of 1.58 × 10 ⁻⁸ A / whereas the cm ^2, and after 120 seconds of hydrogen radical treatment for 5 seconds with an oxygen gas flow rate of 200 SCCM, in the oxygen experiments # 12 radicals by the processing was carried out, the mean relative permittivity is 3.72, the leakage current In experiment # 13, in which hydrogen radical treatment was performed for 120 seconds, followed by treatment with oxygen radicals at a pressure of 400 Pa for 5 seconds at a hydrogen gas flow rate of 200 SCCM, the average ratio was 1.47 × 10 ⁻⁸ A / cm ² a dielectric constant of 3.53, leakage current 8.94 × 10 ^-9 a / cm ² next; after hydrogen radical treatment for 120 seconds, 20 seconds at an oxygen gas flow rate of 5 SCCM, oxygen radicals In Experiment # 14 processing was performed by an average relative dielectric constant 3.50, leakage current 7.60 × 10 ^-9 A / cm ² next; After hydrogen radical treatment for 120 seconds, the oxygen gas flow rate 200SCCM In experiment # 15 where the treatment with oxygen radicals was performed for 20 seconds at an average relative dielectric constant of 3.50 and a leak current of 8.54 × 10 ⁻⁹ A / cm ² ; after 120 seconds of hydrogen radical treatment In Experiment # 16, in which treatment with oxygen radicals was performed at an oxygen gas flow rate of 5 SCCM for 40 seconds, the average relative dielectric constant was 3.35, and the leakage current was 4.75 × 10 ⁻⁹ A / cm ² ; 120 seconds In experiment # 17 in which treatment with oxygen radicals was performed for 40 seconds at an oxygen gas flow rate of 200 SCCM after hydrogen radical treatment, an average relative dielectric constant of 3.58 and a leakage current of 7.96 × 10 ⁻⁹ A / cm ²

  FIGS. 11A and 11B show the relationship between the process time and the leakage current for the samples having an oxygen gas flow rate ratio of 0.1 and 0.025 to Ar gas during the oxygen radical treatment from FIG. 11A and 11B also show the results of the standard sample (# 11) not subjected to the oxygen radical treatment and the results of the sample with the pressure during the oxygen radical treatment being 400 Pa. In FIG. 11A, the horizontal axis indicates the process time, and in FIG. 11B, the oxygen gas / Ar gas flow rate ratio.

  11A and 11B, the leak current value decreases rapidly with the oxygen radical treatment time, and in particular, the sample with an oxygen gas / Ar gas flow rate ratio of 0.0025 during the oxygen radical treatment has a leak more than the sample with 0.1. It can be seen that the current is low.

  From the relationship between FIGS. 11A and 11B, it is understood that such oxygen radical treatment is preferably performed for 10 seconds or longer, more preferably for 20 seconds or longer.

  12A and 12B show the relationship between the process time and the leakage current based on FIG. 14 for samples having an oxygen gas flow rate ratio of 0.005 and 0.025 to hydrogen gas during the oxygen radical treatment. FIG. 12B also shows the result of the standard sample (# 1) not subjected to the oxygen radical treatment. However, in FIG. 12A, the horizontal axis indicates the process time, and in FIG. 12B, the oxygen gas / hydrogen gas flow rate ratio.

  Referring to FIGS. 12A and 12B, the leakage current value decreases with the progress of the oxygen radical treatment. In particular, in the case of a sample having an oxygen gas / hydrogen gas flow rate ratio of 0.025 during the oxygen radical treatment, the process time is about 60 times. It can be seen that the leakage current value starts to rise after the second.

  On the other hand, in the experiment in which the flow ratio of oxygen gas to hydrogen gas is 0.005, the k value and the leakage current value are not increased even when a longer process time is used.

  From the relationship between FIGS. 12A and 12B, it is understood that such oxygen radical treatment is preferably performed for 10 seconds or more, more preferably for 20 seconds or more.

  FIG. 15 shows the XPS (Xray-photoelectron spectroscopy) spectra of the SiOCH film samples obtained in the experiment # 2 in FIG. 13 and the experiment # 12 in FIG. 14, and the # 1 in FIG. It shows in comparison with the XPS spectrum of the SiOCH film sample obtained in the comparative control experiment.

Referring to FIG. 15, in the comparative sample, a peak corresponding to Si—C or Si—Si bond is observed. It can be seen that these bonds in the film are reduced and substantially disappeared both when (H radical) and O * (O radical) are used, and when only O * is used. This means that the surface of the SiOCH film is modified to a SiO ₂ rich composition by O *.

  16 and 17 show XPS depth profiles of Si, O, and C obtained for the SiOCH film thus formed.

Referring to FIGS. 16 and 17, the data described as “Ref” indicates that the sample censored in the steps of FIGS. 10A to 10C is the data described as “Post O 2”. 10), the sample in which the surface of the SiOCH film was subjected to oxygen plasma treatment and the sample described as “H ₂ + O ₂ ” were treated with oxygen radicals and nitrogen radicals in the step of FIG. 10D. Samples are shown.

  In particular, from the enlarged view of FIG. 17, on the surface portion of the SiOCH film constituting the reference samples (# 1 and # 11) having a thickness of 20 to 30 nm, a damage layer reduced by hydrogen radicals of FIG. However, in such a surface damage layer, the ratio of Si—C bonds increases, causing problems such as an increase in leakage current and an increase in relative dielectric constant. It can also be seen that oxygen desorption occurs in the oxygen-rich surface densified layer 43 formed on the surface of the SiOCH film 42A by the hydrogen plasma treatment. That is, the surface densified layer formed in the process of FIG. 10B is considered to have a thickness of about 20 to 30 nm.

  On the other hand, in this embodiment, by performing oxygen plasma treatment or hydrogen and oxygen plasma treatment as post-treatment in the step of FIG. 10D, such depletion of oxygen in the surface portion of the SiOCH film is replenished. Further, the damage is repaired, and the reduction of the relative dielectric constant and the leakage current as shown in FIGS. 11A and 11B are realized.

Note that the process of FIG. 10D can be executed by performing the above process in the process chamber 300 when the cluster type substrate processing apparatus 60 described in FIG. 8 is used.

[Third Embodiment]
In the embodiment described above, the densified layer 43 is left on the formed porous SiOCH film 42A. The densified layer 43 increases the relative dielectric constant of the entire SiOCH film. Since it works, it is desirable to remove it.

  Therefore, in the present embodiment, the densified layer 43 is removed by, for example, an Ar sputtering process or a CMP process in the densified layer removing process of FIG. 18 subsequent to the process of FIG.

  For example, the process of FIG. 18 is performed using a plasma processing apparatus 400, supplying Ar gas at a flow rate of 5 SCCM at a substrate temperature of 280 ° C., for example, supplying a high frequency of 13.56 MHz to a high frequency coil with a power of 300 W, The densified layer 43 can be removed by applying a high-frequency bias having a frequency of 2 MHz to the substrate to be processed with a power of 300 W and performing sputter etching for 130 seconds. As a result, the surface densified layer is removed, the relative dielectric constant of about 2.2 can be reduced to 2.0, and an ultra-low dielectric constant film can be formed.

  FIG. 19 shows the configuration of a cluster type substrate processing apparatus 60A for performing the film forming process according to the present embodiment including the process of FIG. However, in FIG. 19, the same reference numerals are assigned to the portions corresponding to the portions described above, and the description thereof is omitted.

  Referring to FIG. 19, a substrate processing apparatus 60A includes a processing chamber 400 coupled to the vacuum transfer chamber 601 through a gate valve 601c. In the processing chamber 400, an ICP plasma processing apparatus is provided in the illustrated example. Is provided. In addition, a microwave plasma processing apparatus can be provided in the processing chamber 400.

  Therefore, the substrate to be processed after the step of FIG. 2C or the step of FIG. 10D in the processing chamber 300 is transferred to the processing chamber 400 via the vacuum processing chamber 601 by the transfer mechanism 602. The surface densified layer removing process 18 is performed by a sputtering method.

Further, the substrate to be processed which has completed the process of FIG. 2C or the process of FIG. 10D in the process chamber 300 is taken out from the load lock chamber 603 or 604, and is transferred to another CMP apparatus in FIG. It is also possible to carry out the process.

[Fourth Embodiment]
2B or 10B described above, after the SiOCH film 42 is formed in the process of FIG. 2A or 10A, Ar gas and oxygen gas, Further, a desired surface densified layer forming step is performed by continuously supplying high-frequency power and shutting off only the organosilane source gas.

  The inventor of the present invention generates a large amount of particles on the surface of the substrate to be processed in the experiment of FIGS. 2A to 2C, particularly in the termination process of the SiOCH film forming process of FIG. Found that there is a case.

  FIG. 20 shows an experiment conducted by the inventors of the present invention.

  Referring to FIG. 20, a SiOCH film 42 is formed in step 1, and a film formation end process is performed in steps 2-4. The SiOCH film 42 is formed at a substrate temperature of 45 ° C.

In Experiment # 21, the supply of trimethylsilane source gas and the supply of oxygen gas were shut off at the same time as the radio frequency power was shut off, and after Ar gas was flowed for 0.1 second in Step 2, the processing was finished in Step 3. . In this experiment # 21, it was confirmed by SEM observation that particles having a particle size of 0.1 μm or more were formed on the surface of the substrate to be processed at a density of 1 × 10 ⁸ particles / cm ² .

In Experiment # 22, the high-frequency power was cut off while continuing the supply of the trimethylsilane source gas, the supply of oxygen gas, and the supply of Ar gas in Step 1, and after 10 seconds in Step 2, the trimethylsilane source gas, oxygen gas and Ar The gas supply is shut off. In Experiment # 22, it was confirmed by SEM observation that particles having a particle size of 0.13 μm or more were formed on the surface of the substrate to be processed at a density of 5 × 10 ⁷ particles / cm ² .

In Experiment # 23, the supply of the trimethylsilane source gas was shut off while continuing the supply of oxygen gas and Ar gas in Step 2 and the supply of high-frequency power. The supply of oxygen gas and high frequency power is cut off while the supply of gas is continued. Further, in step 4, the supply of Ar gas is cut off after 10 seconds. In this experiment # 23, it was confirmed by measurement with a particle counter that particles having a particle size of 0.13 μm or more were formed on the surface of the substrate to be processed at a density of 0.06 particles / cm ² .

In Experiment # 24, the supply of oxygen gas and trimethylsilane source gas was shut off while continuing the supply of Ar gas and high-frequency power in Step 2, and the supply of Ar gas was continued in 0.1 seconds after Step 3 The supply of high-frequency power is cut off. Further, in step 4, the supply of Ar gas is cut off after 10 seconds. In Experiment # 24, it was confirmed by SEM observation that particles having a particle size of 0.1 μm or more were formed on the surface of the substrate to be processed at a density of 2 × 10 ⁷ particles / cm ² .

In Experiment # 25, while the Ar gas was continuously supplied in Step 2, the trimethylsilane source gas, oxygen gas, and high-frequency power were shut off, and in Step 3, the Ar gas supply was shut off after 10 seconds. In this experiment # 22, it was confirmed that particles having a particle size of 0.13 μm or more were formed on the surface of the substrate to be processed at a density of 2 × 10 ⁷ particles / cm ² .

In Experiment # 26, only the supply of oxygen gas was cut off while continuing the supply of trimethylsilane gas, Ar gas, and high-frequency power in Step 2, and in Step 3, the supply of Ar gas was continued 0.1 seconds later. The supply of silane gas and high frequency power is cut off. Further, in step 4, the supply of Ar gas is cut off after 10 seconds. In Experiment # 26, it was confirmed by SEM observation that particles having a particle size of 0.13 μm or more were formed on the surface of the substrate to be processed at a density of 5 × 10 ⁷ particles / cm ² .

  From the above results, when the SiOCH film is formed by the plasma CVD method in the parallel plate type substrate processing apparatus as in Experiment # 23, the supply of the trimethylsilane source gas is first stopped, and then the oxygen gas and the high frequency are supplied. It can be seen that stopping the power supply is effective in suppressing particle generation.

  Such a film formation end sequence is actually equivalent to performing the densification process step of FIG. 2B after the film formation step of FIG. In the step (C) or the steps in FIGS. 10A to 10D, it can be seen that as a result, the generation of particles accompanying the completion of the formation of the SiOCH film is minimized.

  Furthermore, the inventor of the present invention searched for optimum post-processing conditions that can suppress the generation of particles using the parallel plate type substrate processing apparatus 11 of FIG.

  FIGS. 21A to 21C show the process of FIGS. 2A and 2B with the oxygen plasma treatment time of FIG. 2B changed at a process pressure of 600 Pa where particles are most likely to be generated. The state of particle generation when the However, in FIGS. 21A to 21C, the gap of the substrate processing apparatus 11 is set to 25 mm and the substrate temperature is set to 45 ° C. In the process of FIG. 2A, the flow rates of trimethylsilane gas, oxygen gas and Ar gas are set. The SiOCH film was formed by supplying a high frequency of 13.56 MHz for 6.8 seconds while setting to 100 SCCM, 100 SCCM and 600 SCCM, respectively, while in the process of FIG. Only the oxygen plasma treatment is performed for 20 to 45 seconds. 21A to 21C, the upper diagram shows the in-plane distribution of particles on the substrate surface, and the lower diagram shows the particle size distribution of the generated particles.

  FIG. 21A shows a case where the oxygen plasma treatment time of FIG. 2B is set to 20 seconds, and it can be seen that many particles having a particle diameter of about 0.4 μm or more are generated.

  On the other hand, FIG. 21B shows a case where the oxygen plasma treatment time of FIG. 2B is set to 30 seconds, but the generation of particles having a particle diameter of about 0.4 μm or more is suppressed and generated. It can be seen that most of the particles are those having a particle size of 0.2 μm or less. A similar tendency is also observed in FIG. 21C where the oxygen plasma treatment time is 45 seconds.

  As described above, according to the results of FIGS. 21A to 21C, the oxygen plasma treatment process of FIG. 2B described above is performed for 30 seconds or more as in the case of the results of FIG. It can be seen that the generation of particles at the end of film formation can be effectively suppressed. However, when the particles having a particle size of 0.13 μm or less are observed, the effective generation of particles cannot be suppressed. The range has increased conversely.

  On the other hand, following the process of FIG. 2 (A), in the process of FIG. 2 (B), the flow rates of trimethylsilane gas, oxygen gas and Ar gas are set to 2 while the substrate temperature, process pressure and plasma power remain the same. FIG. 22 (A) shows the state of particle generation when the number is doubled.

  Referring to FIG. 22A, the situation is slightly improved from the case of FIG. 21C, but it can be seen that a large amount of particles having a particle size of 0.1 μm or less are generated.

  Further, in FIG. 22B, after the SiOCH film forming process of FIG. 2A is performed under the same conditions as those of FIG. 21A described above, the oxygen plasma treatment process of FIG. The particle generation state is shown under the same process conditions, except that the flow rates of oxygen gas and Ar gas are doubled for 30 seconds.

  Referring to FIG. 22B, it can be seen that the generation of particles can be dramatically reduced by increasing the flow rates of Ar gas and oxygen gas during the oxygen plasma treatment after the film formation. .

  Further, in FIG. 22C, after the SiOCH film forming process of FIG. 2A is performed under the same conditions as those of FIG. 21A described above, the oxygen plasma treatment process of FIG. The particle generation state is shown under the same process conditions, but with the process pressure reduced to 250 Pa for 30 seconds.

  Referring to FIG. 22C, it can be seen that also in this case, the generation of particles after the film forming process is dramatically reduced.

  FIG. 23A shows the flow rates of oxygen gas and Ar gas in the oxygen plasma treatment of FIG. 2B at 250 Pa, which is lower than the process pressure in the film formation treatment of FIG. ) Shows the state of particle generation when the film forming process is increased twice as much as in the film forming process.

  Referring to FIG. 23 (A), it can be seen that particle generation is further suppressed with respect to both of FIGS. 22 (B) and 22 (C).

  Further, in FIG. 23B, the process pressure at the time of film formation in FIG. 2A is set to 500 Pa, and the film formation end process similar to that in FIG. 23A corresponds to the process in FIG. Shows the state of particle generation.

  As can be seen from FIG. 23B, the generation of particles is further suppressed.

  As described above, the oxygen plasma treatment step of FIG. 2B or FIG. 10B described above is further performed at a lower pressure than the film formation treatment step of FIG. 2A or FIG. By performing the process under conditions where the gas and Ar gas flow rates are increased, it is possible to more effectively suppress the generation of particles.

  In addition, the oxygen plasma treatment at the end of the film formation is not only performed when the SiOCH film is formed in the parallel plate type substrate processing apparatus as shown in FIG. 1, but also as shown in FIGS. In the wave plasma processing apparatus, for example, it is also effective when forming a SiCO film by supplying trimethylsilane gas, Ar gas, and oxygen gas.

In the above description, the case where trimethylsilane (TMS: SiH (CH ₃ ) ₃ ) is used as the organic silicon compound raw material has been described. However, the organic silicon compound raw material of the present invention is not limited to trimethylsilane, Dimethylsilane (SiH ₂ (CH ₃ ) ₂ ), tetramethylsilane (Si (CH ₃ ) ₄ ), dimethyldimethoxysilane (DMDMOS: Si (CH ₃ ) ₂ (OCH ₃ ) ₂ ), dimethyldiethoxysilane (Si ( _{CH 3) 2 (OC 2 H} 5) 2), dimethyl ethoxy silane _{(Si (CH 3) 2 (} OC 2 H 5)), methoxy trimethylsilane _{(Si (CH 3) 3 (} OC 2 H 5)), methyl triethoxysilane _{(Si (CH 3) (OC} 2 H 5) 3), diethyl methyl silane _{(Si (C 2 H 5)} 2 (CH 3)), trimethylsilane ( _{i (C 2 H 5) 2} (CH 3) 3), ethoxy trimethyl silane _{(Si (CH 3) 3 (} OC 2 H 5)), diethoxymethylsilane _{(DEMS: SiH (OC 2 H} 5) 2 (CH ₃ )), ethyltrimethoxysilane (Si (C ₂ H ₅ ) (OCH ₃ ) ₃ ), etc. can also be used.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope described in the claims.

According to the present invention, the porous film is formed by forming a dielectric film containing an organic functional group and a hydroxyl group on the substrate by using an organic silicon compound raw material, and the organic functional group and the hydroxyl group are formed on the surface of the dielectric film. A surface densification layer having a higher density than the dielectric film body is formed on the surface of the dielectric film, and the dielectric film on which the surface densification layer is formed is plasma-excited. In the hole forming step, by performing the step of forming holes in the dielectric film main body by removing the organic functional groups and hydroxyl groups by exposing to the generated hydrogen radicals. , Organic functional groups such as CH ₃ , C ₂ H ₅ ,... Generally abbreviated as CHx, and hydroxyl groups (OH) are discharged out of the film at a controlled rate, Effective shrinkage of dielectric film It is possible to win to become. As a result, an increase in the density of the dielectric film is suppressed, and a porous film having a low dielectric constant can be obtained.

  In addition, after the film forming process, only the film forming source gas is shut off, and the supply of plasma gas and oxidizing gas and the supply of plasma power are engaged, thereby effectively suppressing the generation of particles at the end of the film forming process. As a result, the yield of film formation is greatly improved.

It is a figure which shows the structure of the film-forming processing apparatus used by this invention. (A)-(C) are figures which show the film-forming method by the 1st Embodiment of this invention. It is a figure which shows the structure of the substrate processing apparatus used for porous film formation in this invention. It is another figure which shows the structure of the substrate processing apparatus used for porous film formation in this invention. It is a figure explaining the effect of the said 1st Embodiment of this invention. It is a table | surface which shows process value of the process of FIG. 2 (A)-(C), and k value of the obtained porous membrane. It is a figure which shows the FTIR spectrum of the SiOCH film | membrane obtained by 1st Embodiment of this invention. It is a figure which shows the structure of the cluster type substrate processing apparatus used by 1st Embodiment of this invention. It is a flowchart which shows the film-forming method by 1st Embodiment of this invention performed using the cluster type substrate processing apparatus of FIG. (A)-(D) are figures which show the film-forming method by the 2nd Embodiment of this invention. It is a figure which shows the relationship between the processing time by the 2nd Embodiment of this invention, and leakage current. Is a diagram showing the relationship between O ₂ / Ar flow ratio and the leakage current according to the second embodiment of the present invention. It is a figure which shows the change of the processing time and leakage current by the 2nd Embodiment of this invention. It is a diagram showing a relationship of a second embodiment of the O ₂ / H ₂ flow rate ratio and the leakage current of the present invention. It is a table | surface which shows the experimental condition in 2nd Embodiment. It is another table | surface which shows the experimental condition in 2nd Embodiment. It is a figure which shows the XPS spectrum of the SiOCH film | membrane obtained by the said 2nd Embodiment of this invention. It is a figure which shows the SIMS profile of the SiOCH film | membrane obtained by the said 2nd Embodiment of this invention. It is a figure which expands and shows a part of FIG. It is a figure which shows the 3rd Embodiment of this invention. It is a figure which shows the structure of the cluster type substrate processing apparatus used by the said 3rd Embodiment of this invention. It is a table | surface which shows the experimental conditions in the 4th Embodiment of this invention. (A)-(C) are the figures explaining the 4th Embodiment of this invention. (A)-(C) are another figures explaining the 4th Embodiment of this invention. (A), (B) is another figure explaining the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Parallel plate type substrate processing apparatus 12 Processing container 13 Exhaust port 14 Exhaust apparatus 15 Gate valve 16 Susceptor support stand 17 Susceptor 18 Insulator 19, 27 Refrigerant passage 20 Lifter pin 21, 32 High frequency source 22, 33 Matching device 23 Shower head 24 Gas Supply hole 25 Electrode plate 26 Electrode support 28 Gas inlet 29 Trimethylsilane gas source 30 Oxygen gas source 31 Ar gas source 34 Controller 36 Detoxifier 41 Silicon substrate 42 SiOCH film 42A Porous SiOCH film 43 Densified layer 50 Microwave Plasma processing apparatus 51 Processing vessel 51A Process space 51B Space 51C Exhaust port 51D APD
51E Exhaust system 51G Gate valve 51g Substrate loading / unloading 52 Substrate holding base 52A Heater 52B Drive line 52C Heater power supply 52D Lifter pin 52E Lifting mechanism 53 Top plate 54 Gas ring 55 Microwave antenna 55A Conductor 55B Slow wave plate 55C Flat antenna plate 55a , 55b Slot 56 Coaxial waveguide 56A Outer waveguide 56B Inner conductor 60, 60A Cluster type substrate processing apparatus 101A, 101H, 101O Gas source 103A, 103H, 103O MFC
104A, 104H, 104O, 105A, 105H, 105O, 106 Valve 110A Mode converter 110B Rectangular waveguide 111 Impedance matcher 112 Microwave source 200, 300, 400 Processing chamber 601 Vacuum transfer chamber 601a-601e Gate valve 602 Substrate transfer mechanism 603,604 Load lock room

Claims (21)

Forming a dielectric film containing an organic functional group and a hydroxyl group from an organic silicon compound raw material on a substrate;
Performing a densification treatment to remove the organic functional group on the dielectric film surface, and forming a surface densification layer on the dielectric film surface;
Exposing the dielectric film formed with the surface densified layer to plasma-excited hydrogen radicals and removing the organic functional groups and hydroxyl groups to form vacancies in the dielectric film body; and A method for forming a porous film comprising: The step of forming the dielectric film is performed by a plasma CVD method at a first temperature ranging from room temperature to 200 ° C.,
The step of forming the surface densified layer is performed by plasma treatment at a second temperature ranging from room temperature to 200 ° C.,
The film forming method according to claim 1, wherein the step of forming the holes is performed at a third temperature that is higher than the first and second temperatures.   The film forming method according to claim 2, wherein the first and second temperatures are about 45 ° C., and the third temperature is about 400 ° C. 4.   The step of forming the dielectric film and the step of performing the densification process are continuously performed in the same substrate processing apparatus, and the step of forming the holes is performed in another substrate processing apparatus. The film forming method according to claim 1.   The dielectric film forming step is performed by supplying a raw material gas of the organosilicon compound raw material together with an oxidizing gas and an inert gas to the substrate surface, and the step of forming the surface densified layer includes the dielectric material 2. The film forming method according to claim 1, wherein the film forming process is performed by continuing to supply the oxidizing gas and the inert gas while maintaining plasma, and cutting off only the supply of the source gas.   The film forming method according to claim 5, wherein the step of forming the surface densified layer is terminated by shutting off the supply of the plasma and the oxidizing gas while continuing the supply of the inert gas.   6. The film forming method according to claim 5, wherein the step of forming the surface densified layer is performed by increasing the flow rates of the oxidizing gas and the inert gas as compared with the step of forming the dielectric film.   The film forming method according to claim 1, wherein the step of forming the surface densified layer is performed at a lower process pressure than the step of forming the dielectric film.   The dielectric film is a SiOCH film, and the densification treatment step includes a step of treating the surface of the dielectric film formed on the substrate with plasma-excited oxygen radicals, and the surface densification layer is The film forming method according to claim 1, wherein oxygen is formed at a higher concentration than the dielectric film main body and carbon is contained at a lower concentration than the dielectric film main body.   The film forming method according to claim 1, wherein in the densification treatment step, the surface densification layer is formed to a thickness not exceeding 30 nm.   The film forming method according to claim 1, wherein the densification treatment step is performed such that a Si—O—Si cage structure is formed in the dielectric film body.   The dielectric film forming step and the densifying treatment step are performed in a parallel plate type plasma CVD apparatus while supplying a plasma power of 100 to 750 W under a pressure of 100 to 1000 Pa. The film-forming method of Claim 2 performed while supplying the plasma power of 100-750 W under the pressure of 100-1000 Pa in a microwave plasma processing apparatus.   The film forming method according to claim 1, further comprising a step of post-processing the dielectric film having the surface densified layer in an oxidizing atmosphere after the hole forming step.   The film forming method according to claim 13, wherein the post-processing step is performed by plasma-excited oxygen radicals.   The film forming method according to claim 14, wherein in the post-processing step, plasma-excited hydrogen radicals are further added.   The film forming method according to claim 13, wherein the post-processing step is performed in the same plasma processing apparatus in succession to the hole forming step.   The film forming method according to claim 1, further comprising a step of removing the surface densified layer after the hole forming step.   The film forming method according to claim 17, wherein the step of removing the surface densified layer is performed after the post-processing step.   The film forming method according to claim 17, wherein the removing step is performed by sputtering with a plasma containing a rare gas.   The film forming method according to claim 18, wherein the removing step is performed by a chemical mechanical polishing step. A computer-readable recording medium recording a program for controlling a substrate processing system by a general-purpose computer and causing the substrate processing system to perform a porous film forming process on a silicon substrate, wherein the substrate processing system includes: The substrate processing apparatus of 1 and the second substrate processing apparatus are combined, and the film forming process of the porous film is as follows:
Introducing a substrate to be processed into the first substrate processing apparatus;
In the first substrate processing apparatus, a step of forming a dielectric film containing an organic functional group and a hydroxyl group on the substrate with an organic silicon compound raw material;
In the first substrate processing apparatus, performing a densification treatment to remove the organic functional group on the dielectric film surface, and forming a surface densification layer on the dielectric film surface;
Introducing the substrate to be processed that has undergone the densification treatment into the second substrate processing apparatus;
In the second substrate processing apparatus, the dielectric film on which the surface densified layer is formed is exposed to plasma-excited hydrogen radicals, and the organic functional groups are removed to empty the dielectric film body. Forming a hole, and a computer-readable recording medium.