Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
  • H10P50/286—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of organic materials
  • H10P50/287—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of organic materials by chemical means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32458—Vessel
  • H01J37/32522—Temperature
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32623—Mechanical discharge control means
  • H01J37/32633—Baffles
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32623—Mechanical discharge control means
  • H01J37/32642—Focus rings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/3266—Magnetic control means
  • H01J37/32688—Multi-cusp fields
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/32—Processing objects by plasma generation
  • H01J2237/33—Processing objects by plasma generation characterised by the type of processing
  • H01J2237/334—Etching
  • H01J2237/3341—Reactive etching

Definitions

• the present invention relates to a method and apparatus for plasma etching an organic material film such as a low dielectric constant film (10 ⁇ -11 film) formed on a substrate such as a semiconductor wafer.
• an interlayer insulating film is formed between wiring layers, and the interlayer insulating film is etched to make the wiring layer conductive.
• the interlayer insulating film a film having a lower dielectric constant has been required in order to further increase the speed of a semiconductor device, and an organic material film has been used as such a low dielectric constant film. is there.
• Etching of such an organic material film is performed by plasma etching using an inorganic material film such as silicon oxide as a mask.
• a plasma etching apparatus provided with a pair of parallel plate electrodes is used.
• a semiconductor wafer (hereinafter simply referred to as a wafer) is placed on a lower electrode (supporting electrode), which is one of the parallel plate electrodes, and high frequency power of a frequency of 13.3.56 MHz is applied to the supporting electrode.
• a lower electrode supporting electrode
• high frequency power of a frequency of 13.3.56 MHz is applied to the supporting electrode.
• N 2 , H 2 , Ar, etc. are used as the processing gas supplied into the processing container.
• the organic material film is etched with a high selectivity while preventing such shoulder drop. Therefore, if a molecular single gas or mixed gas is used except for atomic gas such as Ar gas having strong etching action (strong sputtering action), the electron density (plasma density ) Force Very poor uniformity, such as high at the center of the substrate and low at the edge. Therefore, the uniformity of the obtained etching must be poor. In particular, when the diameter of the wafer is increased to 300 mm, such non-uniformity of the electron density (plasma density) becomes more remarkable. Disclosure of the invention
• the present invention has been made in view of such circumstances, and has a high selectivity with respect to an adjacent inorganic material film when etching an organic material film, and a uniform electron density or plasma density. It is an object of the present invention to provide a method and an apparatus for plasma etching that can be etched at a high level.
• the plasma density is dominant in the etching of the organic material film and the contribution of ion energy is small, whereas the etching of the inorganic material film has a low plasma density and ion energy. Both were found to be necessary.
• the ion energy of the plasma can be indirectly grasped by the self-bias voltage of the electrode at the time of etching.
• the self-bias voltage of the electrode is small, so that even if an atomic gas such as Ar is used as the processing gas, the The ability to etch a material film is not very high, but rather a gas that ionizes with low energy, such as Ar, or a gas that has a large ionization cross section It has been found that the electron density, that is, the plasma density can be made uniform by using GaN.
• a method of plasma etching an organic material film on a substrate using a parallel plate type plasma etching apparatus wherein a frequency of a high frequency power for forming a plasma is the 4 O MH z above and then, the ionization energy of the ionization energy or metastable state from the ground state 1 0 e V or less, and the process gas maximum ionization cross section comprises a 2 X 1 0 1 6 cm 2 or more gas A plasma etching of the organic material film using the method.
• the frequency of the high-frequency power for forming plasma is raised to 4 OMHz or higher, which is lower than the conventional frequency.
• a voltage can be realized, and the organic material film can be etched with a high etching selectivity with respect to the inorganic material film.
• a r, X e, ionization energy of ionizing energy or metastable state from the ground state represented by K r is 1 0 e V or less, and the maximum ionization cross section is 2 X 1 0 1 6 cm 2 or more
• the ionization energy of the ionization energy or metastable state from the ground state 1 0 e V or less, and the maximum ionization cross section is 2 X 1 0 1 6 cm 2 or more gas ionized easily another Me, added this By doing so, ionization of the processing gas is promoted.
• the processing gas can be sufficiently ionized even in the vicinity of the edge of the substrate having a low electric field intensity, and the processing gas is uniformly ionized as a whole, so that the electron density, that is, the plasma density becomes uniform. .
• this method includes a processing container to which the processing gas is supplied, a support electrode provided in the processing container and supporting the substrate, and a counter electrode facing the support electrode. It can be performed using a plasma etching apparatus provided with a parallel plate electrode configured as described above. In this case, by applying high-frequency power (at a frequency of 4 O MHz or higher) for forming plasma on the support electrode, the etching of the inorganic material film with less damage to the inorganic material film in a state where the self-bias voltage of the support electrode is low. It can be performed.
• the supporting electrode may be applied to high-frequency power at a frequency of 500 kHz ⁇ 27 MH Z for ion attraction to the substrate.
• ions can be drawn in a range where damage to the inorganic material film is small, so that the etching property can be improved.
• the counter electrode not the supporting electrode
• ions at a frequency of 500 kHz to 27 MHz
• the absolute value of the self-bias voltage of the support electrode is set to 500 V or less in order to reduce damage to the inorganic material film.
• Ar is most effective because it has a metastable state from which it can transition to an ionized state at about 4 eV, has a large maximum ionization cross section, and is inexpensive among these.
• Xe and Kr also have metastable states, from which they can transition to the ionized state with relatively low energy, and have a large maximum ionization cross section.
• a processing gas containing Ar, N 2 and H 2 , or a processing gas containing Ar and NH 3 can be used.
• the frequency of the high-frequency power for plasma formation may be 40 MHz or more, but 10 OMHz can be suitably used.
• the distance between the supporting electrode and the counter electrode (inter-electrode distance) in the parallel plate electrode be 4 Omm or less. That is, according to Paschen's law, the discharge starting voltage V s takes a minimum value (the minimum value of Paschen) when the product pd of the gas pressure and the distance A between the electrodes is a certain value. The value of pd, which takes the minimum value of Paschen, decreases as the frequency of the high-frequency power increases. Therefore, when the frequency of the high-frequency power is relatively large as in the present invention, the discharge starting voltage Vs is reduced to facilitate and stabilize the discharge. A needs to be small. Therefore, in the present invention, the distance between the electrodes is preferably set to 4 Omm or less. Also, by setting the distance between the electrodes to 4 Omm or less, the residence time of the gas in the processing vessel can be shortened. As a result, the reaction products are efficiently discharged from the processing vessel, The effect that the stop can be reduced is also obtained.
• an apparatus for plasma etching an organic material film on a substrate comprising: a processing container for accommodating the substrate; and a processing container provided in the processing container.
• a parallel plate electrode composed of a support electrode supporting the substrate, a counter electrode facing the support electrode, a processing gas supply system for supplying a processing gas into the processing container, an exhaust system for exhausting and against the support electrode, and the first high frequency power supply for supplying high frequency power to form a plasma, wherein the first high frequency power source, frequency 4 O MH Z or
• the processing gas supply system has an ionization energy from the ground state or an ionization energy from the metastable state of 10 eV or less, and a maximum ionization cross-sectional area of 2 ⁇ 10 16 cm 2 or more.
• Gas containing processing gas Providing an apparatus.
• an apparatus for plasma-etching an organic material film on a substrate comprising: a processing container for accommodating the substrate; a processing container provided in the processing container; A parallel plate electrode composed of a support electrode on which is supported, a counter electrode facing the support electrode, a processing gas supply system for supplying a processing gas into the processing container, and an exhaust for exhausting the processing container A first high-frequency power supply for supplying high-frequency power for forming plasma to the counter electrode; and a second high-frequency power supply for supplying high-frequency power for ion attraction to the support electrode.
• the first high frequency power supply supplies a frequency 4 O MH Z or more high-frequency power
• the second high-frequency power source high frequency of 5 0 0 k H z ⁇ 2 7 MH z Power is supplied to the support electrode
• the gas is supplied so that the absolute value of the bias voltage is 500 V or less
• the processing gas supply system has ionization energy from the ground state or ionization energy from the metastable state of 100 eV or less and maximum ionization.
• An apparatus is provided, which supplies a processing gas containing a gas having a cross-sectional area of 2 ⁇ 10 16 cm 2 or more.
• FIG. 1 is a cross-sectional view showing one embodiment of a plasma etching apparatus according to the present invention
• FIG. 2 is a horizontal cross-sectional view schematically showing a ring magnet arranged around a processing vessel of the apparatus of FIG.
• FIG. 3 is a diagram showing the relationship between the electron energy of various gases and the ionization cross section
• FIG. 4 is a diagram showing the relationship between the electron energy of the rare gas and the ionization cross section;
• FIG. 5 is a schematic cross-sectional view partially showing a plasma processing apparatus in which a high-frequency power supply for plasma generation and a high-frequency power supply for ion attraction are connected to a support table serving as a support electrode;
• Fig. 6 is a schematic cross-sectional view partially showing a plasma processing apparatus in which a high-frequency power supply for plasma generation is connected to a shower head, which is a counter electrode, and a high-frequency power supply for ion attraction is connected to a support table, which is a support electrode.
• a high-frequency power supply for plasma generation is connected to a shower head, which is a counter electrode
• a high-frequency power supply for ion attraction is connected to a support table, which is a support electrode.
• FIG. 7a and 7b are cross-sectional views showing a structural example of a wafer to which the plasma etching of the present invention is applied;
• FIG. 8 is a diagram showing the relationship between the self-bias voltage V dc and the plasma density Ne when the frequency of the high-frequency power is 4 O MHz and 10 O MHz in an argon gas plasma;
• Fig. 9a and Fig. 9b show the uniformity of the plasma density (electron density) of each gas.
• Fig. 10 shows the case of using N 2 ZH 2 which is usually used as a processing gas. Diagram showing the relationship between the radial position of the wafer and the plasma density (electron density);
• FIG. 11 is a diagram showing a relationship between a radial position of a 30 O mm wafer and a plasma density when N 2 / H 2 is used as a processing gas and when Ar is further added; Is a diagram showing the relationship between the radial position of a 30 O mm wafer and the plasma density when NH 3, which is commonly used as a processing gas, is used and when Ar is further added;
• Figure 13 shows the flow rate of Ar gas in the processing gas and the etching rate of the organic and inorganic material films in the wafer radial direction when the organic material film was actually etched using the inorganic material film as a mask.
• Figure 14 is a diagram showing the relationship between the Ar flow rate and the etching uniformity in the wafer radial direction, and the relationship between the Ar flow rate and the average etching rate;
• FIGS. 15a and 15b are diagrams showing the relationship between the Ar flow rate and the etching selectivity of SiLK to Si ⁇ ⁇ ⁇ ⁇ 2 .
• FIG. 1 is a sectional view showing a plasma etching apparatus used for carrying out the present invention.
• This etching apparatus is air-tight, has a substantially cylindrical shape, and has a processing vessel 1 ′ made of aluminum whose walls are oxidized, for example, on the surface.
• This processing vessel 1 is grounded.
• a support table 2 which horizontally supports the wafer W as a substrate and functions as a support electrode (lower electrode) is provided.
• the table 2 is made of, for example, aluminum whose surface is oxidized, and is supported via an insulating member 4 on a support portion 3 protruding from a low wall of the processing container 1.
• a focus ring 5 made of a conductive material or an insulating material is provided on the outer periphery above the table 2. When the diameter of the wafer W is 300 mm ⁇ , the focus ring 5 has a diameter of 340 to 380 mm ⁇ .
• a baffle plate 14 is provided outside the focus ring 5.
• a cavity 7 is formed between the table 2 and the bottom wall of the processing vessel 1.
• An electrostatic chuck 6 for electrostatically attracting the wafer W is provided on the surface of the table 2.
• the electrostatic chuck 6 has an electrode 6a interposed between insulators 6b, and a DC power supply 13 is connected to the electrode 6a. Then, when a voltage is applied to the electrode 6a from the power source 13, the semiconductor wafer W is attracted by, for example, Coulomb force.
• a refrigerant flow path 8a is provided in the table 2, and a refrigerant pipe 8b is connected to the refrigerant flow path 8a.
• An appropriate refrigerant is supplied by the refrigerant control device 8 through the refrigerant pipe 8b.
• the refrigerant is supplied to the refrigerant passage 8a and circulated.
• the temperature of the table 2 can be controlled to an appropriate temperature.
• the cooling air circulated through the refrigerant flow path 8a The heat of the medium can be efficiently transmitted to the wafer W, and the temperature controllability of the wafer W can be improved.
• a power supply line 12 for supplying high-frequency power is connected to almost the center of the table 2, and a matching unit 11 and a high-frequency power supply 10 are connected to the power supply line 12. High frequency power of a predetermined frequency is supplied to the table 2 from the high frequency power supply 10.
• shower heads 16 are provided in parallel with each other, facing the table 2 functioning as a supporting electrode, and the shower head 16 is grounded via a processing container. Therefore, the shower head 16 functions as a counter electrode (upper electrode), and forms a pair of parallel plate electrodes together with the table 2.
• the distance (inter-electrode distance) between these tables (supporting electrodes) 2 and the shower head (counter electrode) 16 is preferably set to 4 O mm or less. That is, according to Paschen's law (Paschen's 1 aw), the discharge starting voltage Vs takes a minimum value (Paschen minimum value) when the product pd of the gas pressure and the distance between the electrodes is a certain value.
• the value of pd which takes the minimum value of Paschen, decreases as the frequency of the high-frequency power increases. Accordingly, when the frequency of the high-frequency power is relatively large as in the present embodiment, the discharge starting voltage Vs is reduced to facilitate and stabilize the discharge. Distance A needs to be reduced.
• the residence time of the gas in the processing container 1 can be shortened.
• the reaction product can be efficiently discharged from the inside of the processing container 1, and the effect that the etching stop can be reduced can be obtained.
• the shower head 16 is fitted into the top wall of the processing container 1.
• the shower head 16 has a shower head body 16a and an electrode plate 18 that is replaceably provided on the lower surface thereof.
• a number of gas discharge holes 17 are provided to penetrate the electrode plate 18 at the bottom of the shower head body 16a, and a gas inlet is provided at the top of the shower head body 16a. 16b, and a space 16c is formed inside.
• a gas supply pipe 15a is connected to the gas introduction section 16b, and the other end of the gas supply pipe 15a is supplied with a processing gas for supplying a processing gas for etching. Device 15 is connected.
• a gas obtained by adding an ionization-promoting gas to a molecular gas such as N 2 , H 2 , ⁇ 2 , CO, NEU, or C x H y (where x and y are natural numbers) is used.
• the "ionization promoting gas” the ionization energy of the metastable state also is properly ionization energy from the ground state 1 0 e V or less, and the maximum ionization cross section is 2 X 1 0 16 cm 2 or more gas It is.
• Ar, Xe, and Kr are preferable as such an ionization promoting gas.
• Ar is particularly preferable.
• the ionization energy of Ar from the ground state is 15.8 eV, which is not much different from molecular gases such as N 2 and H 2, but Ar has a metastable state that can be held for about 5 seconds. It exists at the energy level of 11.55 eV and 11.72 eV from the state, and from its metastable state, it can transition to the ionized state at about 4 eV.
• Ar has a maximum ionization cross section of about 3 ⁇ 10 16 cm 2 , which is larger than molecular gases such as N 2 and H 2 .
• Xe and Kr also have metastable states, can transition to the ionized state with relatively low energy, and have a larger maximum ionization cross section than Ar, as shown in Fig. 4.
• He and Ne have small maximum ionization cross sections as shown in Fig. 4.
• He and Ne have a large ionization energy.
• the ionization energy from the ground state is 24.6 eV.
• a combination of N 2 and H 2, NH 3, a combination of these with 0 2, the combination of N 2 and 0 2, the combination of CH 4 or C 2 H 6 and ⁇ 2, etc. can be mentioned.
• a combination of N 2 and H 2 and NH 3 are preferred. Therefore, as a combination of the processing gases, a combination of Ar, N 2 and H 2, and a combination of Ar and NH 3 are preferable.
• the flow ratio of the ionization promoting gas to the molecular gas in the processing gas is preferably in the range of 0.5 or more.
• Such processing gas flows from the processing gas supply device 15 to the space 16c in the shower head main body 16a via the gas supply pipe 15a and the gas introduction part 16b, and the gas is discharged. It is discharged from the outlet 17 and is used for etching the film formed on the wafer W.
• An exhaust pipe 19 is connected to the bottom wall of the processing container 1, and an exhaust device 20 including a vacuum pump and the like is connected to the exhaust pipe 19.
• an exhaust device 20 including a vacuum pump and the like is connected to the exhaust pipe 19.
• the vacuum pump of the exhaust device 20 By activating the vacuum pump of the exhaust device 20, the pressure inside the processing vessel 1 can be reduced to a predetermined degree of vacuum.
• a gate valve 24 that opens and closes the loading / unloading port 23 for the wafer W is provided above the side wall of the processing container 1.
• two ring magnets 21a and 21b are arranged concentrically so as to go around the processing container 1 above and below the loading / unloading port 23 of the processing container 1, and the table 2 and the shaft 2 are arranged in a concentric manner.
• a magnetic field is formed around the processing space between the processing space and the space 16.
• the ring magnets 2 la and 21 b are rotatably provided by a rotating mechanism (not shown).
• the ring magnets 21 a and 2 lb are configured by arranging a plurality of segment magnets 22 composed of permanent magnets in a ring shape while being supported by a support member (not shown). Have been.
• 16 segment magnets 22 are arranged in a multipole state in a ring shape (concentric shape). That is, in the ring magnets 2 la and 2 lb, the magnetic poles of the plurality of adjacent segment magnets 22 are arranged to be opposite to each other, so that the magnetic force lines are adjacent as shown in the drawing.
• a magnetic field of 5 T (300 to 450 Gauss) is formed, and the wafer arrangement portion is substantially in a magnetic-free state.
• the reason why the magnetic field strength is defined in this way is that if the magnetic field is too strong, it causes a leakage magnetic field, and if it is too weak, the plasma confinement effect cannot be obtained.
• the appropriate magnetic field strength also depends on the structure of the device, the range varies depending on the device.
• the magnetic field strength on the focus ring 5 be 0.001 T (10 Gauss) or more.
• EXB drift electron drift motion
• the magnetic field strength of the existing portion be less than 0.001 T (l OG auss).
• Substantially no magnetic field state in the wafer arrangement part means not only when the magnetic field does not completely exist, but also because no magnetic field that affects the etching processing is formed in the wafer arrangement part, which substantially affects the wafer processing. This includes the case where there is no magnetic field.
• a portion of the wall of the processing container 1 corresponding to the magnetic pole may be locally cut.
• a rotating mechanism not shown
• the container wall is prevented from being locally shaved.
• Each of the segment magnets 22 is rotatable about a vertical axis by a segment magnet rotating mechanism (not shown). By rotating the segment magnets 22 in this manner, it is possible to switch between a state in which a multi-pole magnetic field is substantially formed and a state in which a multi-pole magnetic field is not formed. Depending on the conditions, the multipole magnetic field may or may not effectively act on the wafer processing.Therefore, it is possible to switch between the state in which the multipole magnetic field is formed and the state in which the multipole magnetic field is not formed. The appropriate one can be selected according to the conditions.
• segment magnets is not limited to this example.
• cross-sectional shape is not limited to a rectangle as in this example, but may be any shape such as a circle, a square, a trapezoid, and the like.
• the magnet material forming the segment magnets 22 is not particularly limited, either.
• known magnet materials such as rare earth magnets, fluorite magnets, and alnico magnets can be used.
• the high frequency power for generating plasma and the high frequency power for attracting ions in the plasma are superimposed.
• a high-frequency power source 26 for ion pull-in is connected to the matching unit 11 in addition to the high-frequency power source 10 for plasma generation, and these are superimposed.
• the high-frequency power source 26 for attracting ions preferably has a frequency of 500 kHz to 27 MHz. Thereby, the ion energy can be controlled to further increase the etching rate of the organic material film.
• the supply of the high-frequency power from the high-frequency power supply 26 for ion attraction is performed so that the absolute value of the self-bias voltage Vdc of the table 2 as the supporting electrode becomes 500 V or less. More preferably, the absolute value of V dc is 200 V or less.
• a high-frequency power source 10 ′ for plasma formation is connected to a shower head 16, which is a counter electrode, via a matching box 11, and ions are drawn into a table 2, which is a support electrode. Only the high frequency power supply 26 may be connected via the matching unit 11. In this case, since the etching does not proceed unless a bias is applied to the table 2, the high-frequency power source 26 for ion attraction is essential. Also in this case, the supply of the high-frequency power from the high-frequency power supply 26 for ion attraction is performed so that the absolute value of the self-bias voltage V dc of Table 2 as the supporting electrode becomes 500 V or less. Do. More preferably, the absolute value of Vdc is 200 V or less.
• the high-frequency power supply 10, matching device 11, DC power supply 13, processing gas supply device 15, refrigerant control device 8, heat transfer gas supply device 9, exhaust device 20, etc. are controlled by the control unit 25. Is done.
• the wafer W before etching has an organic material film 42, which is a 1 ow-k film, formed as an inter-layer insulating layer on a silicon substrate 41, and a hard mask is formed thereon.
• An inorganic material film 43 having a predetermined pattern is formed, a BARC layer 44 is formed thereon, and a resist film 45 having a predetermined pattern is formed thereon.
• the inorganic material film 43 is made of a material used as a general hard mask, and is preferably made of silicon oxide, silicon nitride, or silicon oxynitride. Can be mentioned.
• the organic material film 42 to be etched is a 1 ow-k film used as an interlayer insulating film as described above, and has a relative dielectric constant extremely smaller than that of a silicon oxide which is a conventional interlayer insulating layer material.
• Examples of such an organic material-based 1 ow-k film include bisbenzocyclobutene resin (BCB) and polyolefins such as SiLK (trade name) and FLARE (trade name) manufactured by Dow Chemical Co., Ltd.
• Organic polysiloxane resins such as arylene ether resin (PAE) and methyl silsesquioxane (MSQ).
• the organic polysiloxane has a structure including a functional group containing C and H in a bonding structure of a silicon oxide film as described below.
• R represents an alkyl group such as a methyl group, an ethyl group, or a propyl group or a derivative thereof, or an aryl group such as a fuunyl group or a derivative thereof.
• the ARC layer 44 and the inorganic material film 43 are etched using the resist film 45 as a mask to obtain the structure shown in FIG. 7B. At this time, the thickness of the resist film 45 is reduced by etching.
• etching is performed using the organic material film 42 of the wafer W having such a structure with the resist film 45 and the inorganic material film 43 as masks.
• the gate valve 24 of the apparatus shown in FIG. 1 is opened, the wafer W having the structure shown in FIG. 7B is carried into the processing vessel 1 by the transfer arm, placed on the table 2, and then the transfer arm is moved.
• the gate valve 24 is closed, and the inside of the processing container 1 is evacuated to a predetermined degree of vacuum through the exhaust pipe 19 by the vacuum pump of the exhaust device 20.
• a predetermined molecular gas and an ionization promoting gas are introduced into the processing container 1 from the processing gas supply device 15 at a predetermined flow ratio.
• N 2 and H 2 and Ar are respectively 180 m LZ min, 180 ml / min, 3 Introduce at a flow rate of 6 OmL ZixLin, and maintain the inside of the processing vessel 1 at a predetermined pressure, for example, about 1.33 to 133.3 Pa (10 to 100 mTorr).
• the high-frequency power source 10 supplies the table 2 with high-frequency power having a frequency of 4 OMHz or more, for example, 10 OMHz, while maintaining the predetermined pressure.
• a predetermined voltage is applied from the DC power supply 13 to the electrode 6a of the electrostatic chuck 6, and the wafer W is attracted by, for example, a cooler.
• the processing gas supplied to the processing space is turned into plasma, and the organic material film 42 is etched by the plasma.
• the resist film 45 functions as a mask halfway, but during the etching, the resist film 45 and the 81 layer 44 are etched and disappear, and thereafter, the inorganic material film is formed. Etching of the organic material film 42 is continued using only 43 as a mask.
• the ring magnets 21a and 21b in a multi-pole state form a magnetic field as shown in Fig. 2 around the processing space, thereby exhibiting a plasma confinement effect.
• the etching rate of the wafer W can be made uniform.
• such a magnetic field may not have such an effect.
• the segment magnet 22 is rotated so that the magnetic field is not substantially formed around the processing space. Just do it.
• the uniformity of the plasma processing can be further enhanced by the conductive or insulating focus ring 5 provided around the wafer W on the table 2. That is, when the focus ring 5 is formed of a conductive material such as silicon-SiC, the plasma formation region spreads over the focus ring 5 because the focus ring region functions as a supporting electrode, and the wafer W The plasma processing in the peripheral portion is promoted, and the uniformity of the etching rate is improved. When the focus ring 5 is made of an insulating material such as quartz, the charge cannot be transferred between the focus ring 5 and the electron ion in the plasma. And the uniformity of the etching rate can be improved.
• the etching of organic materials is dominated by plasma density and the contribution of ion energy is small, whereas the etching of inorganic materials requires both plasma density and ion energy. Therefore, in the etching of the organic material film 42 using such an inorganic material film 43 as a mask, the etching of the inorganic material film 43 is performed without lowering the etching rate of the organic material film 42. To increase the etching selectivity, it is necessary to lower the ion energy without lowering the plasma density.
• the organic material film can be formed even if an atomic gas such as Ar is contained. Only 42 is selectively etched at a high etching rate.
• the ion energy of the plasma can be indirectly grasped by the self-bias voltage of the electrode at the time of etching, so that the etching rate of the organic material film 42 is not reduced and a high etching selectivity is obtained.
• FIG. 8 is a diagram showing the relationship between the self-bias voltage V dc on the abscissa and the plasma density on the ordinate, and the relationship between the high-frequency power frequencies 4 O MHz and 10 O MHz, Shows the result of using Ar for evaluation.
• the values of the plasma density Ne and the self-bias voltage Vdc were changed by changing the applied high-frequency power. That is, as the high-frequency power applied at each frequency increases, both the plasma density Ne and the self-bias voltage Vdc increase.
• the plasma density was measured with a microwave interferometer. As shown in Fig. 8, when the frequency of the high-frequency power is 4 OMHz, the organic material film is self-biased at a plasma density of 1 X 10 1 ⁇ ⁇ m_ 3 that can achieve a practical etching rate. When the voltage V dc shows a low value of 300 V and the frequency is 100 MHz, the self-bias voltage V dc becomes less than 100 V at a plasma density of 1 X 101 1 cm-- 3 . Further decline.
• the high frequency power for plasma generation and the high frequency power for attracting ions in the plasma can be superimposed.
• the frequency and the power are adjusted so that the absolute value of the self-bias voltage Vdc of Table 2 as the support electrode is 50 OV or less, preferably 200 V or less.
• high frequency power of 4 O MHz or more for plasma formation can be applied to the shower head 16 which is a counter electrode, and in this case, The application of high-frequency power for attracting ions is essential, but also in this case, the absolute value of the self-bias voltage Vdc of Table 2 which is the supporting electrode is 500 V or less, preferably 200 V or less. Adjust the frequency and power as needed.
• the absolute value of the self-bias voltage is as small as 500 V or less. Even if a gas is used as the processing gas, the energy is small and the ability to etch the inorganic material film 43 is not so high. Rather, ionization promoting gas, represented by Ar In other words, by using a gas that is ionized with low energy and has a large maximum ionization cross section, it becomes possible to make the electron density, that is, the plasma density uniform.
• the ionization energy from the ground state represented by A r, X e, and K r or the ionization energy from the metastable state is 10 eV or less, and the maximum ionization cross section is 2 X 10 16 cm 2 or more of ionization-promoting gas is added, so that the processing gas becomes easily ionized and near the edge of the substrate where the electric field strength is low.
• the processing gas can be sufficiently ionized even in the side portions, and as a result, the electron density, that is, the plasma density becomes uniform.
• Figures 9a and 9b show the uniformity of the plasma density (electron density) of each gas.
• the pressure inside the processing vessel was set to 4 Pa
• the magnetic field around the wafer was set to 0.003 T (30 Guss)
• high frequency power of 2400 W and 1200 W at 100 MHz was applied to the supporting electrode, and the The relationship between the radial position of the Omm wafer and the plasma density was determined.
• a r is the ionization acceleration gas is substantially uniform You can see that there is.
• FIG. 10 is a diagram showing the relationship between the radial position of a 300 mm wafer and the plasma density (electron density) when N 2 / H 2, which is generally used as a processing gas, is used.
• This Kodewa the processing chamber pressure 4 P a, the wafer peripheral magnetic field and 0. 03 T (300 G uss) , N 2 flow rate: as 1 80 mL / min,: 1 80 m L / min, H 2 flow rate
• High-frequency power of 600 W, 1200 W and 2400 W was applied to the supporting electrode at 10 OMHz. From this figure, it can be seen that the plasma density at the center is high and the distribution is non-uniform at any power with N 2 / H 2 .
• FIG. 11 is a diagram showing the relationship between the radial position of a 30 Omm wafer and the plasma density when N 2 / H 2 is used as a processing gas and when Ar is further added.
• the pressure inside the processing vessel is 4 Pa
• the magnetic field around the wafer is 0.03 T (300 Gu ss)
• the N 2 flow rate is 180 mL / min
• the H 2 flow rate is 180 mL / min
• the Ar flow rate is The frequency was changed to 0, 200, and 40 OmL / min, and high-frequency power of 2400 W was applied to the supporting electrode at 10 OMHz. From this figure, it can be seen that the addition of Ar to N 2 ZH 2 significantly improves the uniformity of the plasma density.
• FIG. 12 is a diagram showing the relationship between the plasma density and the position in the radial direction of a 30 Omm wafer when NH 3, which is generally used as a processing gas, is used, and when Ar is further added.
• the pressure inside the processing vessel is 4 Pa
• the magnetic field around the wafer is 0.03 T (300 G uss)
• the NH 3 flow rate is 24 OmL / mi ⁇
• the Ar flow rate is 0 and 24 OmL / min.
• a high-frequency power of 2400 W was applied to the supporting electrode at 10 OMHz. From this figure, it can be seen that by adding Ar to NH 3 , It can be seen that the degree of uniformity is greatly improved.
• the processing vessel is a case in which a SiC (a trade name) manufactured by Dow Chemical is used as an organic material film and SiO 2 is used as an inorganic material film on a 300 mm wafer.
• the internal pressure is 4 Pa
• the magnetic field around the wafer is 0.03 T (300 Guss)
• the N 2 flow rate is 18 OmL / min
• the H 2 flow rate is 18 OmL / min.
• the Ar flow rate was changed to 0, 360, and 72 OmL / min
• etching was performed by applying a high-frequency power of 240 W at 100 OMHz to the support electrode.
• FIG. 13 is a diagram showing the etching rates of the organic material film and the inorganic material film in the wafer radial direction at this time.
• two orthogonal directions (X direction and y direction) were used as the radial direction of the wafer. From this figure, it can be seen that the addition of Ar also improves the uniformity of the etching rate.
• FIG. 14 is a diagram showing the relationship between the above-mentioned etching experiment, where the horizontal axis represents the Ar flow rate, and the vertical axis represents the etching uniformity and average etching rate in the radial direction. As shown in this figure, it was confirmed that the addition of Ar improves the uniformity of the etching rate without lowering the etching rate. Further, it was confirmed that the uniformity became better as the Ar flow rate increased.
• FIG. 15a and FIG. 15b show the etching flow rate and the etching selectivity of SiLK to SiO2 (SiLK / SiO2; hereinafter simply referred to as etching selection) for the above etching experiment. Ratio).
• FIG. 15A shows the etching selectivity with respect to the position in the wafer radial direction when the Ar flow rate is OmLZmin and 36 OmL / minm72 OmL / min.
• Fig. 15b shows the relationship between the Ar flow rate and the etching selectivity at the center and the edge 5min. As shown in these figures, it was confirmed that the etching selectivity did not decrease with the addition of Ar, but rather that the addition ratio improved with the addition of Ar, and that the addition of Ar acted in the direction of reducing the shoulder drop of the mask. Was.
• the present invention can be variously modified without being limited to the above embodiment.
• a plurality of seg Although a multi-pole ring magnet in which a ring magnet is arranged around the processing vessel is used, it is not limited to this as long as a magnetic field can be formed around the processing space to confine the plasma. Absent. Further, such a peripheral magnetic field for confining the plasma is not always necessary, and the etching may be performed in the absence of the magnetic field. Alternatively, plasma etching may be performed in an orthogonal electromagnetic field by applying a horizontal magnetic field to the processing space.
• a 1 ow-k film is used as the organic material film.
• the present invention is not limited to this, and another film such as an organic material film used for a multilayer resist can be applied.
• the explanation was given centering on Ar as the ionization accelerating gas, and Xe and Kr as examples.
• the ionization energy from the ground state or the ionization energy from the metastable state is 10 eV or less, and The gas is not limited to these as long as the gas has a maximum ionization cross section of 2 ⁇ 10 16 cm 2 or more.
• the present invention is not limited to this, and the organic material film is selectively applied to the inorganic material film. It can be applied to all cases where it is necessary to etch a base material film.
• the present invention can be applied to asking for removing a resist used as a mask when etching an inorganic material film such as SiO 2 formed on a substrate such as a Si wafer. .
• the present invention since it is necessary to selectively remove the resist film as the organic material film efficiently without etching the underlying inorganic material film as much as possible, by applying the present invention to the assing, Good asshing characteristics can be obtained.
• the present invention is not limited to this, and the present invention can be applied to plasma etching of an organic material film formed on another substrate. .

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