Source: https://patents.justia.com/patent/7771796
Timestamp: 2020-01-19 05:08:40
Document Index: 98017717

Matched Legal Cases: ['art 10', 'art 10', 'art 34', 'art 34', 'art 34', 'art 34', 'art 34', 'art 36', 'art 34']

US Patent for Plasma processing method and film forming method Patent (Patent # 7,771,796 issued August 10, 2010) - Justia Patents Search
Justia Patents Plasma (e.g., Cold Plasma, Corona, Glow Discharge, Etc.)US Patent for Plasma processing method and film forming method Patent (Patent # 7,771,796)
Plasma processing method and film forming method
Nov 4, 2005 - Tokyo Electron Limited
A plasma processing method of carrying out curing processing on a low dielectric constant film produced on a to-be-processed substrate by applying plasma thereto in a processing chamber of a plasma processing apparatus, includes the steps of: a) introducing, in the plasma processing chamber, a first gas having a function of stabilizing plasma and a second gas generating active hydrogen, and, after that; b) generating plasma, and carrying out curing processing on the low dielectric constant film.
An object of the present invention is to provide a plasma processing method by which, when curing processing is carried out on a Low-k film, the Low-k film can be made to have a reduced dielectric constant, curing can be carried out uniformly through out the entirety of the film, and also, adherence can be improved.
FIG. 8 shows a relationship between a depth of a SiOCH film and a Si—CH3/Si—O ratio in a comparison example and in the present invention;
FIG. 9 shows a relationship between a depth of a SiOCH film and a Si—H/Si—O ratio in a comparison example and in the present invention;
FIG. 10 shows a relationship between a depth of an SiOCH film and a Si—CH3/Si—O ratio according to the present invention;
FIG. 11 shows a relationship between a depth of an SiOCH film and a Si—H/Si—O ratio according to the present invention;
Embodiments of the present invention are described specifically with reference to figures.
A Low-k film may be formed, for a SiOCH series film for example, with an organosilicon compound such as a tetramethylsilane (TMS), 1,1,3,3-tetramethyldisiloxane (TMDS), cyclohexyldimethoxymethylsilane (CHDMMS) or such applied as a raw material, with the use of a parallel flat plate type (electric capacitance type) plasma CVD apparatus, a configuration of which is well-known, under predetermined pressure and temperature with an oxidant such as oxygen. Preferably, a to-be-processed substrate is brought in a plasma CVD apparatus for example, an organosilicon compound and an oxidant are introduced at a flow rate in a range of 100 to 300 mL/min. and with a flow rate in a range of 100 to 300 mL/min., respectively, with a pressure in a range of 133 to 400 Pa (or 1 to 3 Torrs), at a temperature of the to-be-processed substrate in a range of 0 to 70° C., a high frequency electric power of hundreds of kilohertz is provided with an output in a range of 200 to 300 W, plasma processing is carried out, and thus, film forming can be achieved. As other plasma, inductive coupling plasma (ICP) may be applied.
FIG. 1 shows a sectional view, diagrammatically showing one example of a plasma processing apparatus in which a Low-k film curing processing according to one embodiment of the present invention is carried out. In this plasma processing apparatus, microwave is introduced in a processing chamber with the use of a planar antenna having a plurality of slots, in particular, an RLSA (Radial Line Slot Antenna), and thus, plasma is generated. Thus, the plasma processing apparatus is configured as an RLSA microwave plasma processing apparatus, and thereby, microwave plasma with a high density at a low electron temperature can be generated. Such a type of processing apparatus is one which is preferably applicable for curing a Low-k film, for example. This plasma processing apparatus is configured to have an air tight structure, and has an approximately cylindrical chamber 1 which is grounded. A circular opening part 10 is produced at an approximately center of a bottom wall 1a of the chamber 1, and, also, an exhaust container 11, which communicates with the opening part 10 and projects downward, is provided in the bottom wall 1a.
Inside the chamber 1, a susceptor 2 (mount table), made of ceramics such as AlN, is provided for horizontally supporting a wafer W or a dummy wafer Wd, acting as a to-be-processed substrate, is provided. This susceptor 2 is supported by a cylindrical supporting member 3, made of ceramics such as AlN, extending upward from a bottom center of the exhaust container 11. A guide ring 4 is provided for guiding the wafer W in the periphery of the susceptor 2. Further, in the susceptor 2, a resistance heating type heater 5 is embedded, and, this heater 5 heats the susceptor 2 with power supply from a heater power source 6, and heats the wafer W, the to-be-processed substrate. At this time, a temperature can be controlled in a range of a room temperature to 800° C., for example. On an inner circumferential wall of the chamber 1, a cylindrical liner 7, made of quartz, is provided.
An exhaust pipe 23 is connected to a side wall of the above-mentioned exhaust container 11, and an exhaust system 24 including a high-speed vacuum pump is connected to the exhaust pipe 23. As a result of the exhaust system being operated, a gas in the chamber 1 is uniformly discharged to a space 11a of the exhaust container 11, and is discharged via the exhaust pipe 23. Thereby, the inside of the chamber 1 is reduced in pressure in a predetermined vacuum state, for example, 0.133 Pa at a high speed.
Above the microwave transmitting plate 28, a disk-shaped or angle-shaped planar antenna member 31 is provided, to face the susceptor 2. This planar antenna member 31 is mounted on a top end of the side wall of the chamber 1. The planar antenna member 31 is made of, for example, a copper plate or an aluminum plate, a surface of which is plated by gold or silver, and is configured in such a manner that plural microwave radiation holes 32 (slots) are provided in a predetermined pattern, each of which passes through a body of the planar antenna member 31. These microwave radiation holes 32 are like long grooves, as shown in FIG. 2, and, typically, are disposed in such a manner that each adjacent microwave radiation holes 32 form a ‘T’ letter, and these microwave radiation holes 32 are disposed concentrically. Lengths, arrangements and separations of these microwave radiation holes 32 are determined depending on a wavelength of microwave actually applied, or such. It is noted that, in FIG. 2, Δr denotes a separation, in a radial direction, between adjacent microwave radiation holes 32 disposed concentrically. The microwave radiation holes 32 may have other shapes, for example, circular shapes, arc shapes, or such. Further, arrangement of the microwave radiation holes 32 are not limited. Other than the concentric arrangement, a spiral arrangement, a radial arrangement or such may be applied.
On the top surface of the chamber 1, a shield lid part 34 made of metal material such aluminum, stainless steal or such is provided to cover the planar antenna member 31 and the slow wave member 33. The top surface of the chamber 1 and the shield lid part 34 are sealed by a sealing member 35. Cooling water flow paths 34a are provided in the shield lid part 34, and, by flowing cooling water therethrough, the shield lid part 34, the slow wave member 33, the planar antenna member 31 and the microwave transmitting plate 28 are cooled. The shield lid part 34 is grounded.
The waveguide tube 37 has a coaxial waveguide tube 37a, having a circular sectional shape, extending upward from the opening part 36 of the shield lid part 34, and a rectangular waveguide tube 37b, having a rectangular sectional shape, connected to a top part of the coaxial weave guide tube 37b via a mode transducer 40 and extending horizontally. The mode transducer 40 between the coaxial waveguide tube 37a and the rectangular waveguide tube 37b has a function of transducing microwave propagating in a TE mode in the rectangular waveguide tube 37b into a TEM mode. An inner conductor 41 extends at a center of the coaxial waveguide tube 37a, and the inner conductor 41 is connected to a center of the planar antenna member 31 at a bottom. Thereby, microwave is efficiently and uniformly made to propagate to the planar antenna member 31 via the inner conductor 41 of the coaxial waveguide tube 37a.
The respective parts of the plasma processing apparatus 100 are connected with and controlled by a process controller 50 including a CPU. The process controller 50 has a user interface 51 including a keyboard for inputting commands for managing the plasma processing apparatus 100, a display device for displaying operation states of the plasma processing apparatus 100, and so forth.
Specifically, for example, the inert gas flow rate of Ar or such is set in a range of 50 to 1000 mL/min (sccm), and the H2 gas flow rate is set in a range of 50 to 2000 mL/min (sccm). The inside of the chamber 1 is adjusted in a processing pressure in a range of 13.3 to 1333 Pa (or 100 [mTorrs] to 10 [Torrs]), or more preferably, in a range of 93.3 to 666.5 Pa. A temperature of the wafer W is heated on the order of a range of 300 to 500° C.
That is, microwave from the microwave generating system 39 is lead to the waveguide tube 37 via the matching circuit 38, is then provided to the planar antenna member 31 via the rectangular waveguide tube 37b, the mode transducer 40 and the coaxial waveguide tube 37a in the stated order, and, from the planar antenna member 31, microwave is made to radiate to a space above the wafer W in the chamber 1, via the microwave transmitting plate 28. Microwave propagates in the rectangular waveguide tube 37b in a TE mode, is then transduced into a TEM mode by the mode transducer 40, and then propagates in the coaxial waveguide tube 37b for the planar antenna member 31. By means of radiation of microwave in the chamber 1 via the microwave transmitting plate 28 from the planar antenna member 31, an electromagnetic field is generated in the chamber 1, and thereby, the Ar gas and the H2 gas become plasma. The thus-obtained microwave plasma is high density plasma approximately in a range of 5×1010 to 1×1013/cm3 or more, as a result of the microwave radiating via the many microwave radiation holes 32 of the planar antenna 31. An electron temperature of the plasma is on the order of a range of 0.7 to 2 eV, and uniformity of the plasma density is not more than ±5%. As a result, curing processing can be carried out at a low temperature within a reduced time. Further, since the plasma with the low electron temperature is thus applied, a plasma damage made by ions or such on a foundation layer can be advantageously reduced.
Further, thanks to a function of mainly hydrogen radicals (H*) or hydrogen ions (H+) of the hydrogen rich plasma, Si—CH3 in the film is replaced by Si—CH2—Si for a case where the Low-k film is a SiOCH film for example, bonding becomes strengthened, and thus, curing is achieved.
As can be seen from FIG. 5, in the comparison example, the methyl group light emission intensity sharply increased from the only Ar gas plasma ignition, a state in which the methyl group light emission intensity was high is maintained for 10 seconds in a period (Steps S2 and S3) of the only Ar gas plasma, then the methyl group light emission intensity decreased to the order of 2 after the H2 gas ignition in Step S4, and Ar/H2 plasma was generated. After that, the methyl group light emission intensity behaved stable. That is, since Ar gas plasma has high Ar+ ion energy, bonding of Si—CH3 in the Low-k film was broken, a composition in which Si—H was dominant resulted, and thus, only a surface of the film was hardened.
Next, after curing processing was carried out on a SiOCH film in a condition differed as described below, the film was cut obliquely from a surface to a foundation layer, and a composition analysis was carried out on the cut surface in FT-IR (Fourier Transform Infrared Spectroscopy). FIG. 8 shows a relationship between a depth of the cut surface (nm) and a ratio between Si—CH3 and Si—O (Si—CH3/Si—O). FIG. 9 shows a relationship between a depth of the cut surface (nm) and a ratio between Si—H and Si—O (Si—H/Si—O).
Wafer temperature=400° C.; and
From FIGS. 8 and 9, according to the present invention in which plasma ignition was carried out after the H2 gas was introduced, each of the Si—CH3/Si—O ratio and the Si—H/Si—O ratio had an approximately constant value, without regard to a measurement depth from the vicinity of a surface. In contrast thereto, in the comparison example in which plasma ignition was carried out before the H2 introduction, the Si—CH3/Si—O ratio was low in the vicinity of the film surface, and, contrary thereto, the Si—H/Si—O ratio was high in the vicinity of the film surface. This was presumably because, in the vicinity of the surface of the SiOCH film, a methyl groups were eliminated by a function of the Ar ions.
After curing processing was carried out in the following conditions, each film was cut obliquely from a surface to a foundation layer, and a composition analysis was carried out on the cut surface in FT-IR. FIG. 10 shows a relationship between a depth of the cut surface (nm) and a ratio between Si—CH3 and Si—O (Si—CH3/Si—O). FIG. 11 shows a relationship between a depth of the cut surface (nm) and a ratio between Si—H and Si—O (Si—H/Si—O).
From FIGS. 10 and 11, it can be seen that the Si—CH3/Si—O ratio on the film surface increased, and thus, elimination of methyl groups was further inhibited, in a case where the plasma ignition was made after the H2 gas introduction with the ratio Ar:H2=1:10, in comparison to the case of the ratio Ar:H2=1:2. From this result, it has been seen that, in terms of improvement of film quality obtained after the curing, curing processing should be carried out preferably in a high H2 gas ratio in which generation of active hydrogen such as hydrogen radicals (H*) increased there. Further, it has been also seen that, a further satisfactory result could be obtained as a result of the pressure being increased.
Further, FIG. 14 shows IR spectrums of the films obtained through the curing according to the present invention method and the comparison method (where an absorbance was shown in a normalized value). It is seen that, the SiOCH film cured according to the present invention has a larger peak exhibiting Si—CH3 bondings, as well as an elimination of methyl groups was inhibited, in comparison to the SiOCH film cured according to the comparison method. That is, it is presumed that, in the curing processing in which the Ar plasma ignition was made before the H2 gas introduction, Si—H was likely to be generated as a result of Si—CH3 bondings being broken, while breakage of Si—CH3 bondings was inhibited in the processing in which the Ar+H2 plasma ignition was made after the H2 gas introduction.
a flow rate ratio between the inert gas and the H2 gas (inert gas: H2 gas) lies in a range of 1:2 to 1:20.
a flow rate ratio between the inert gas and H2 gas (inert gas: H2 gas) lies in a range of 1:2 to 1:20.
6103601 August 15, 2000 Lee et al.
6374770 April 23, 2002 Lee et al.
7250370 July 31, 2007 Chang et al.
9-167767 June 1997 JP
2003-503849 January 2003 JP
WO 03/095702 November 2003 WO
Patent number: 7771796
Patent Publication Number: 20060099799
Inventors: Masayuki Kohno (Amagasaki), Masaru Sasaki (Amagasaki)
Application Number: 11/266,308
Current U.S. Class: Plasma (e.g., Cold Plasma, Corona, Glow Discharge, Etc.) (427/535); Coating Formed From Vaporous Or Gaseous Phase Reaction Mixture (e.g., Chemical Vapor Deposition, Cvd, Etc.) (427/255.28)
International Classification: H05H 1/00 (20060101); C23C 16/00 (20060101);