WO2012026117A1 - プラズマ処理装置及び光学モニタ装置 - Google Patents
プラズマ処理装置及び光学モニタ装置 Download PDFInfo
- Publication number
- WO2012026117A1 WO2012026117A1 PCT/JP2011/004698 JP2011004698W WO2012026117A1 WO 2012026117 A1 WO2012026117 A1 WO 2012026117A1 JP 2011004698 W JP2011004698 W JP 2011004698W WO 2012026117 A1 WO2012026117 A1 WO 2012026117A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- monitor
- light
- substrate
- mesh
- processing apparatus
- Prior art date
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 123
- 238000009832 plasma treatment Methods 0.000 title description 2
- 239000000758 substrate Substances 0.000 claims abstract description 55
- 238000012544 monitoring process Methods 0.000 claims abstract description 52
- 238000012545 processing Methods 0.000 claims description 115
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 31
- 230000005540 biological transmission Effects 0.000 claims description 24
- 239000004020 conductor Substances 0.000 claims description 22
- 239000010453 quartz Substances 0.000 claims description 19
- 238000010926 purge Methods 0.000 claims description 17
- 239000005350 fused silica glass Substances 0.000 claims description 10
- 230000001902 propagating effect Effects 0.000 claims description 3
- 238000004904 shortening Methods 0.000 claims description 3
- 238000001039 wet etching Methods 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 abstract description 27
- 239000013307 optical fiber Substances 0.000 abstract description 17
- 238000001020 plasma etching Methods 0.000 abstract description 10
- 230000001427 coherent effect Effects 0.000 abstract description 9
- 238000001816 cooling Methods 0.000 abstract description 2
- 230000005670 electromagnetic radiation Effects 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 71
- 239000010408 film Substances 0.000 description 39
- 238000000034 method Methods 0.000 description 28
- 238000005530 etching Methods 0.000 description 27
- 230000008569 process Effects 0.000 description 22
- 229910004298 SiO 2 Inorganic materials 0.000 description 12
- 230000005855 radiation Effects 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 238000002834 transmittance Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000012546 transfer Methods 0.000 description 6
- 238000011065 in-situ storage Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000012806 monitoring device Methods 0.000 description 3
- 239000003507 refrigerant Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000000427 thin-film deposition Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/55—Specular reflectivity
-
- 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
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32192—Microwave generated discharge
-
- 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
- H01J37/32917—Plasma diagnostics
- H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge
- H01J37/32972—Spectral analysis
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/3065—Plasma etching; Reactive-ion etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
- H01L22/26—Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
- H01L29/66568—Lateral single gate silicon transistors
- H01L29/66575—Lateral single gate silicon transistors where the source and drain or source and drain extensions are self-aligned to the sides of the gate
- H01L29/6659—Lateral single gate silicon transistors where the source and drain or source and drain extensions are self-aligned to the sides of the gate with both lightly doped source and drain extensions and source and drain self-aligned to the sides of the gate, e.g. lightly doped drain [LDD] MOSFET, double diffused drain [DDD] MOSFET
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates to a plasma processing apparatus for performing desired processing on a substrate to be processed using plasma generated by microwave discharge.
- plasma is often used in order to cause a favorable reaction to a processing gas at a relatively low temperature.
- plasma generated using high frequency discharge in the MHz range or plasma generated using microwave discharge in the GHz range has been widely used for this type of plasma treatment.
- Plasma generated using microwave discharge has the advantage of being able to generate high-density plasma with a low electron temperature under low pressure, and is particularly advantageous by adopting a slot antenna and a plate-like microwave introduction window structure. A diameter plasma can be generated efficiently. Further, since a magnetic field is not required, the plasma processing apparatus can be simplified.
- radial line slot antennas in particular, have large plasma density uniformity and controllability by radiating microwaves uniformly and over a wide range from a slot plate having a large number of concentrically arranged slots. A plasma having a diameter can be generated.
- a process performed in a processing container may be controlled in real time through in-situ monitoring.
- the optical waveguide for monitoring does not affect the uniformity of the electromagnetic wave radiation characteristics of the slot antenna and thus the uniformity of the plasma density. It is necessary to have a simple device configuration.
- the optical monitor device mounted on the microwave plasma processing apparatus disclosed in Patent Document 1 is the final section of the microwave transmission line that transmits the microwave generated from the microwave generator toward the processing container.
- the inner conductor of the coaxial line is constituted by a hollow tube. By passing light through the hollow tube, the process performed in the processing vessel is optically monitored in-situ.
- This optical monitor device is provided with a hole for an optical waveguide that passes through the center of the slot antenna so as to be continuous with the hollow tube (inner conductor) of the coaxial line.
- the center of a flat slot antenna is the center of a radial waveguide, and even if a through hole for an optical waveguide is formed at this location, the uniformity of electromagnetic wave radiation characteristics of the slot antenna is not affected. There is no hindrance to density uniformity or controllability.
- the conventional optical monitor device disclosed in Patent Document 1 has a difficulty in providing an optical waveguide for monitoring in a microwave transmission line (coaxial line).
- a microwave transmission line coaxial line
- lamp light when non-coherent light having a wide wavelength range as described above is used as monitor light, an optical waveguide having a sufficiently large aperture, that is, a light amount cannot be obtained.
- the conventional optical monitor device has a restriction that a hollow tube (internal conductor) of a microwave transmission line (coaxial line) cannot be used as a processing gas supply path.
- the present invention solves the problems of the prior art as described above, and does not affect the uniformity of the electromagnetic wave radiation characteristics of the flat slot antenna, so that monitor light having a wide wavelength region (particularly non-coherent monitor light) is provided.
- An optical monitor device and a plasma processing apparatus are provided which can perform optical monitoring on the surface of a substrate to be processed in a processing container with high accuracy.
- the plasma processing apparatus of the present invention includes a processing container capable of being evacuated, in which at least a part of the top plate is made of a dielectric window, a substrate holding part for holding a substrate to be processed in the processing container,
- the dielectric includes a processing gas supply unit for supplying a desired processing gas into the processing container, and one or a plurality of slots for radiating microwaves into the processing container, A slot plate of a conductor provided on the window, and a microwave for supplying a microwave into the processing vessel through the slot plate and the dielectric window in order to generate plasma of the processing gas by microwave discharge A supply unit; and an optical monitor unit that optically monitors or measures the surface of the substrate in the processing container via a mesh-shaped through hole formed in the slot plate and the dielectric window. That.
- the optical monitor device of the present invention accommodates a substrate to be processed in a evacuable processing container in which at least a part of a top plate is made of a dielectric window, supplies a processing gas into the processing container, and A microwave is supplied into the processing vessel through a slot plate of a conductor having one or a plurality of slots provided on the body window and the dielectric window, and plasma of the processing gas is generated by microwave discharge.
- an optical monitoring apparatus for optically monitoring or measuring the surface of the substrate, the light source generating monitor light
- a light receiving unit for converting the reflected light from the substrate to the monitor light into an electrical signal, and subjecting the electrical signal from the light receiving unit to predetermined signal processing to monitor information or monitoring
- a monitor circuit for outputting a data result, a mesh-like through hole formed in the slot plate for passing the monitor light and the reflected light from the surface of the substrate, and the monitor light passing through the mesh of the slot plate.
- the surface of the substrate on the substrate holding part is irradiated through the through hole and the dielectric window, and the reflected light from the surface of the substrate is taken in through the mesh window of the dielectric window and the slot plate.
- the microwave supplied from the microwave supply unit is radiated into the processing container from the slot of the slot plate through the dielectric window, and the processing gas is ionized by the microwave electric field.
- plasma is generated.
- the plasma generated in the vicinity of the dielectric window diffuses downward in the processing container, and under this plasma, a desired process such as microfabrication or thin film deposition is performed on the substrate surface on the substrate holder.
- the optical monitor unit or the optical monitor device optically monitors the surface of the substrate to be processed subjected to such plasma processing in-situ via the optical waveguide for monitoring passing through the conductor slot plate and the dielectric window. Or measure.
- the mesh-shaped through-hole provides an optical waveguide for monitoring, while the microwave supplied from the microwave supply unit makes the mesh-shaped through-hole part the same as other parts other than the slot. Propagate smoothly without leaking. This makes it suitable for propagating monitoring light (especially non-coherent monitoring light) with a wide wavelength range without affecting the uniformity of the electromagnetic wave radiation characteristics of the slot antenna (and hence the uniformity of the plasma density).
- the desired optical monitoring of the surface of the substrate to be processed can be performed stably and reliably with high accuracy.
- monitor light having a wide wavelength region can be obtained without affecting the uniformity of electromagnetic wave radiation characteristics of the flat slot antenna.
- optical monitoring of the surface of the substrate to be processed in the processing container can be performed with high accuracy.
- FIG. 1 shows the structure of the microwave plasma processing apparatus in one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the monitor head and optical waveguide of the optical monitor apparatus in one Embodiment mounted in the plasma processing apparatus of FIG. It is a top view which shows the structure of the mesh-shaped through-hole formed in a slot plate in order to comprise an optical waveguide in the optical monitor apparatus of embodiment. It is sectional drawing which shows the longitudinal cross-section of the light-shielding part in the area
- FIG. 1 shows the configuration of a microwave plasma processing apparatus according to an embodiment of the present invention.
- This microwave plasma processing apparatus is configured as a flat surface wave excitation type microwave plasma etching apparatus using a flat slot antenna.
- a cylindrical vacuum chamber (processing container) 10 made of metal such as aluminum or stainless steel is used. have. The chamber 10 is grounded for safety.
- a disk-shaped susceptor 12 on which a semiconductor wafer W is mounted as a substrate to be processed is horizontally disposed as a substrate holding table that also serves as a high-frequency electrode.
- the susceptor 12 is made of, for example, aluminum, and is supported by an insulating cylindrical support portion 14 that extends vertically upward from the bottom of the chamber 10.
- annular exhaust path 18 is formed between the conductive cylindrical support portion 16 extending vertically upward from the bottom of the chamber 10 and the inner wall of the chamber 10.
- An annular baffle plate 20 is attached to the upper part or the inlet of the exhaust path 18 and one or more exhaust ports 22 are provided at the bottom.
- An exhaust device 26 is connected to each exhaust port 22 via an exhaust pipe 24.
- the exhaust device 26 has a vacuum pump such as a turbo molecular pump, and can depressurize the plasma processing space in the chamber 10 to a desired degree of vacuum.
- a gate valve 28 that opens and closes a loading / unloading port 27 for the semiconductor wafer W is attached.
- a high frequency power source 30 for RF bias is electrically connected to the susceptor 12 via a matching unit 32 and a power feed rod 34.
- This high frequency power supply 30 outputs a high frequency of 13.56 MHz, for example, with a predetermined power suitable for controlling the energy of ions drawn into the semiconductor wafer W.
- the matching unit 32 accommodates a matching unit for matching between the impedance on the high-frequency power source 30 side and the impedance on the load (mainly electrodes, plasma, chamber) side.
- a blocking capacitor for self-bias generation is included.
- an electrostatic chuck 36 for holding the semiconductor wafer W by using electrostatic attraction force is provided, and a focus ring that surrounds the periphery of the semiconductor wafer W in a ring shape outside the electrostatic chuck 36 in the radial direction. 38 is provided.
- the electrostatic chuck 36 is obtained by sandwiching an electrode 36 a made of a conductive film between a pair of insulating films 36 b and 36 c, and a high voltage DC power supply 40 is electrically connected to the electrode 36 a through a switch 42 and a covered wire 43. It is connected.
- the semiconductor wafer W is attracted and held on the electrostatic chuck 36 by an electrostatic force generated by a DC voltage applied from the DC power supply 40.
- an annular refrigerant chamber 44 extending in the circumferential direction is provided inside the susceptor 12.
- a refrigerant having a predetermined temperature such as cooling water cw, is circulated and supplied to the refrigerant chamber 44 via pipes 46 and 48 from a chiller unit (not shown).
- the processing temperature of the semiconductor wafer W on the electrostatic chuck 36 can be controlled by the temperature of the coolant.
- a heat transfer gas such as He gas from a heat transfer gas supply unit (not shown) is supplied between the upper surface of the electrostatic chuck 36 and the back surface of the semiconductor wafer W via the gas supply pipe 50.
- lift pins that can vertically move through the susceptor 12 and a lifting mechanism (not shown) and the like are also provided.
- a circular dielectric window 52 for introducing microwaves is airtightly attached to the ceiling surface of the chamber 10 facing the susceptor 12 as a top plate.
- the dielectric window 52 is made of synthetic quartz having a high transmittance with respect to short-wavelength light (especially ultraviolet rays) in a portion 52a through which the optical waveguide 104 for monitoring passes.
- 52b is made of low-cost fused quartz.
- a flat slot antenna for example, a circular radial slot antenna 55 is provided on the dielectric window 52.
- the radial line slot antenna 55 includes a slot plate 54, a dielectric plate (delay plate) 56, and a metal portion on the top surface of the dielectric plate (the bottom surface of the cover plate 72).
- the slot plate 54 has a large number of slot pairs (54a, 54b) distributed concentrically as slots for radiating microwaves. Further, as will be described in detail later, in the slot plate 54, a mesh-shaped through hole MH is formed in a portion 54c through which the monitoring optical waveguide 104 passes.
- the radial line slot antenna 55 is electromagnetically coupled to the microwave transmission line 58 via a dielectric plate 56 provided on the slot plate 54.
- the dielectric plate 56 is made of synthetic quartz having a high transmittance with respect to light having a short wavelength (especially ultraviolet rays) through a portion 56a through which the optical waveguide 104 for monitoring passes.
- the other portion 56b of the dielectric plate 56 is made of a dielectric having a high dielectric constant suitable for compressing (shortening) the wavelength of the microwave, such as quartz, aluminum oxide, and aluminum nitride.
- it is made of low-cost fused silica.
- the microwave transmission line 58 is a line for transmitting, for example, a 2.45 GHz microwave output from the microwave generator 60 at a predetermined power to the radial line slot antenna 55.
- the waveguide 62 and the waveguide ⁇ A coaxial tube converter 64 and a coaxial tube 66 are provided.
- the waveguide 62 is, for example, a rectangular waveguide, and transmits the microwave from the microwave generator 60 toward the chamber 10 to the waveguide-coaxial tube converter 64 using the TE mode as a transmission mode.
- the waveguide-coaxial tube converter 64 couples the end portion of the rectangular waveguide 62 and the start end portion of the coaxial tube 66 to convert the transmission mode of the rectangular waveguide 62 into the transmission mode of the coaxial tube 66.
- the coaxial tube 66 extends vertically downward from the waveguide-coaxial tube converter 64 to the center of the upper surface of the chamber 10, and the end or lower end of the coaxial line is connected to the center of the slot plate 54 via the dielectric plate 56.
- the coaxial tube 66 is formed of a cylindrical body, and the microwave propagates in the space between the inner conductor 68 and the outer conductor 70 in the TEM mode.
- the microwave output from the microwave generator 60 propagates through the waveguide 62, the waveguide-coaxial tube converter 64, and the coaxial tube 66 of the microwave transmission line 58 as described above, and the radial line slot antenna. Power is supplied to 55 dielectric plates 56.
- the microwave spread in the radial direction while shortening the wavelength in the dielectric plate 56 is a circularly polarized plane wave including two orthogonal polarization components from each slot pair 54a, 54b of the radial line slot antenna 55. Is emitted toward the chamber 10.
- the microwaves radiated into the chamber 10 ionize the nearby gas and generate a plasma with a high density and a low electron temperature.
- the microwave electric field (surface wave electric field) propagates in the radial direction along the surface of the dielectric window 52 and the plasma.
- a cover plate 72 that also serves as an antenna rear plate is provided so as to cover the upper surface of the chamber 10.
- the cover plate 72 is made of aluminum, for example, and has a function of absorbing (dissipating) heat of dielectric loss generated in the dielectric window 52 and the dielectric plate 56 and heat generated according to the process and adjusting the heat to an arbitrary temperature. is doing.
- a coolant having a predetermined temperature for example, cooling water cw, is circulated and supplied from a chiller unit (not shown) to the flow path 74 formed inside the cover plate 72 via pipes 76 and 78.
- the processing gas supply unit 80 includes a processing gas supply source 82 disposed outside the chamber 10, and a manifold or buffer chamber 84 formed in an annular shape in the side wall of the chamber 10 at a position somewhat lower than the dielectric window 52. And a plurality of side wall gas discharge holes 86 provided at equal intervals in the circumferential direction and facing the plasma generation space from the buffer chamber 82, and a gas supply pipe 88 extending from the processing gas supply source 82 to the buffer chamber 84.
- An MFC (mass flow controller) 90 and an on-off valve 92 are provided in the middle of the gas supply pipe 86.
- the processing gas sent from the processing gas supply source 82 at a predetermined flow rate is introduced into the buffer chamber 84 in the side wall of the chamber 10 through the gas supply pipe 88, and then into the buffer chamber 84. After the pressure in the circulation direction is made uniform, the gas is discharged from the side wall gas discharge port 86 substantially horizontally toward the center of the chamber 10 and diffuses into the plasma generation space.
- the control unit 94 includes a microcomputer. Each unit in the plasma etching apparatus, for example, the exhaust device 26, the high-frequency power source 30, the switch 42 for the electrostatic chuck 36, the microwave generator 60, the processing gas supply unit 80, Controls individual operations of the heat transfer gas supply unit (not shown), the optical monitor device 100 described later, and the operation of the entire device.
- a processing gas that is, an etching gas (generally a mixed gas) is introduced into the chamber 10 from the processing gas supply unit 80 at a predetermined flow rate.
- the heat transfer gas He gas
- the switch 42 is turned on to transfer the heat by the electrostatic adsorption force of the electrostatic chuck 36. Hot gas is confined to the contact interface.
- the microwave generator 60 is turned on, and the microwave output from the microwave generator 60 with a predetermined power is propagated through the microwave transmission line 58 and fed to the radial line slot antenna 55, and the radial line slot is supplied. A microwave is radiated from the antenna 55 into the chamber 10. Further, the high frequency power supply 30 is turned on to output a high frequency for RF bias at a predetermined power, and this high frequency is applied to the susceptor 12 via the matching unit 32 and the power feed rod 34.
- the etching gas introduced into the chamber 10 from the side wall gas discharge port 86 of the processing gas supply unit 80 diffuses under the dielectric window 52, and gas particles are ionized by a microwave electric field to generate surface-excited plasma.
- the microwave becomes a surface wave that propagates in the radial direction along the lower surface of the dielectric window 52 (the surface facing the plasma) and the plasma.
- the plasma generated under the dielectric window 52 diffuses downward, and isotropic etching using radicals in the plasma and vertical using ion irradiation with respect to the film to be processed on the main surface of the semiconductor wafer W. Etching is performed.
- This microwave plasma etching apparatus is an optical monitoring apparatus for optically monitoring in-situ or in real time the state of an etching process performed in the chamber 10, for example, the film thickness of a film to be processed that decreases with time. 100.
- the optical monitor device 100 is provided at a position radially inward of the edge of the semiconductor wafer W placed on the susceptor 12 and at a position radially outward of the coaxial tube 66.
- the optical monitor device 100 includes a monitor head 102 disposed on a cover plate 72, a monitoring optical waveguide 104, and a monitor main body 108 optically coupled to the monitor head 102 via an optical fiber 106. is doing.
- the monitoring optical waveguide 104 is provided by vertically cutting the cover plate 72, the dielectric plate 56, the slot plate 54 and the dielectric window 52 vertically downward from the monitor head 102.
- FIG. 2 shows the configuration of the monitor head 102 and the optical waveguide 104.
- the monitor head 102 has a sealable cap-shaped housing 110 made of a conductor, for example, aluminum, and a light reflector 112 and an optical lens 114 are provided in the housing 110 as optical components for monitoring, for example.
- the light reflector 112 is made of aluminum, for example, and has an inclined surface of about 45 ° obliquely downward facing the end surface of the optical fiber 106 that terminates in the housing 110 as shown.
- the monitor light LB emitted horizontally from the optical fiber 106 is reflected vertically downward by the front light reflector 112 and enters the semiconductor wafer W directly below through the optical waveguide 104.
- the reflected light HB emitted vertically upward from the semiconductor wafer W irradiated with the monitor light LB hits the light reflecting plate 112 through the optical waveguide 104, is reflected in the horizontal direction from the light reflector 112, and is reflected on the optical fiber 106. Incident.
- the optical lens 114 radiates the monitor light LB emitted from the optical fiber 106 toward the light reflector 112 at a certain spread angle, condenses the reflected light HB from the light reflector 112, and concentrates it on the optical fiber 106. It comes to capture.
- the optical lens 114 may be integrally attached to the tip of the optical fiber 106 as shown, or may be separated from the optical fiber 106 and disposed at a predetermined position.
- the optical fiber 106 is made of, for example, a two-core FO (Fan-out) cable, and an inner forward cable 106a that transmits the monitor light LB and an outer return cable 106b that transmits the reflected light HB are bundled together.
- the monitor light LB is emitted from the end face of the inner outward cable 106a, and the reflected light HB is incident on the end face of the outer return cable 106b.
- the optical fiber 106 is connected to the monitor head 102 by being housed in a sleeve 116 made of, for example, aluminum, which is airtightly attached to the housing 110.
- the inside of the monitor head 102 is electromagnetically shielded from the outside by the housing 110 and the optical fiber sleeve 116 made of a conductor as described above. Therefore, even if the microwave enters the monitor head 102 from the dielectric plate 56 or the radial line slot antenna 55 through the optical waveguide 104, it does not leak out of the monitor head 102.
- the indoor space of the monitor head 102 is shielded from the atmospheric space and is constantly purged by a purge gas such as nitrogen (N 2 ) gas introduced from a purge gas supply port 118 provided on the upper surface of the housing 110.
- a purge gas such as nitrogen (N 2 ) gas introduced from a purge gas supply port 118 provided on the upper surface of the housing 110.
- the purge gas supply port 118 is connected to a purge gas supply source 122 via a gas supply pipe 120.
- a thick base plate 124 made of a conductor, for example, aluminum is airtightly provided at the bottom of the monitor head 102 in order to fully purse the monitor head 102.
- a through hole 124 a continuous with the through hole 72 a of the cover plate 72 is formed at a position where the optical waveguide 104 passes, and an exhaust flow path 124 b continuous with the exhaust flow path 72 b of the cover plate 72 is formed.
- An outlet of the exhaust passage 124b is connected to an exhaust unit 128 made of, for example, an exhaust fan via an exhaust pipe 126.
- the through-hole 72a which comprises the optical waveguide 104, and the exhaust flow path 72b are connected via the communicating path 72c provided in the lower end.
- the purge gas (N 2 gas) supplied from the purge gas supply port 118 into the housing 110 is filled in the housing 110, and then the through hole 124a of the base plate 124 ⁇ the through hole 72a of the cover plate 72 ⁇ the communication path 72c ⁇ exhaust. It flows through the sealed space of the flow path 72b ⁇ the exhaust flow path 124b of the base plate 124 and is discharged to the outside exhaust section 128.
- the optical monitor device 100 in this embodiment is not a single-wavelength coherent laser beam as the monitor light LB for monitoring the film thickness of the film to be processed of the semiconductor wafer W, but a wide range of, for example, 185 nm to 785 nm.
- the short wavelength (especially 200 nm or less) contained in the monitor light LB is easily absorbed by oxygen, it is significantly attenuated when exposed to the atmosphere.
- the space in the monitor head 102 and the space in the optical waveguide 104 for monitoring are constantly purged by the purge gas (N 2 gas).
- the monitor light LB and the reflected light HB before being taken into the optical fiber 106 are not exposed to the atmosphere and are difficult to attenuate.
- the optical monitoring device 100 improves the monitoring accuracy.
- a mesh-like portion is provided in a portion or region 54c through which the optical waveguide 104 for monitoring passes in the slot plate 54.
- the configuration that forms the through holes MH is also very important.
- the holes MH having a fixed shape and a fixed size are distributed at a fixed density.
- the opening shape of the through hole MH is preferably a polygonal shape rather than a circular shape, and a regular hexagon, that is, a honeycomb structure is most preferable.
- the aperture ratio decreases to 60.3%.
- the opening size of the through hole MH is 1/10 or less of the wavelength in the dielectric window, the leakage of the microwave is remarkably reduced.
- the wavelength of the microwave (2.45 GHz) in the quartz is 61 mm, and therefore the opening size of the through hole MH is preferably 6 mm or less.
- the opening size of the slot pair 54a and 54b for radiating microwaves is, for example, 36 mm for the long side and 6 mm for the short side.
- the optical waveguide passage region (mesh) 54 c is separated and independent from the coaxial tube 66 of the microwave transmission line 58. For this reason, the aperture of the optical waveguide passage region (mesh) 54c can be selected to an arbitrary size within a range that does not affect the uniformity of the electromagnetic wave radiation characteristics of the radial line slot antenna 55. You may choose about 20 mm.
- the monitor light LB incident on the light shielding part TD is reflected obliquely rather than vertically upward, and therefore returns from the light shielding part TD to the monitor head 102. It is possible to reduce stray light that causes a decrease in the SN ratio. This also greatly contributes to increasing the monitoring accuracy of the optical monitor device 100.
- FIG. 4 shows a preferred method for creating the mesh-shaped through hole MH as described above in the slot plate 54 in this embodiment.
- the material of the slot plate 54 is preferably a conductor such as copper or iron-nickel alloy whose surface is gold-plated to ensure good electrical conductivity.
- the iron-nickel alloy has a low linear expansion coefficient, the displacement of the slot plate can be suppressed.
- a mesh-shaped through hole MH is formed by punching, for example.
- the lattice portion of the optical waveguide passage region 54c is still a flat surface.
- an etching solution as shown in FIG. 4 (c)
- it is cut off round from the corner of the edge of each through hole MH, and further the upper surface of the lattice portion. The whole is rounded and becomes convex.
- the etching solution for example, a chemical solution containing an oxidizing agent, an inorganic salt and chlorine ions may be used.
- the surface of the grating portion or the light shielding portion may be rounded to a convex surface, but there is no particular inconvenience even if it is not (even if it is a flat surface).
- the mesh-shaped through-hole MH is formed in the conductor slot plate 54 so as to pass through the optical waveguide 104 for monitoring.
- the portion of the through hole MH is smoothly propagated in the radial direction (without leaking out) in the same manner as the other slot plate portions excluding the slot pairs 54a and 54b.
- monitoring suitable for propagating non-coherent wide-range (multi-wavelength) monitoring light without affecting the uniformity of the electromagnetic radiation characteristics (and hence the uniformity of plasma density) of the radial line slot antenna 55.
- An optical waveguide 104 can be constructed. The degree of freedom in setting the position of the optical waveguide passage region (mesh) 54c on the slot plate 54 is large.
- the optical waveguide passage region (mesh) 54c is guided to an arbitrary position outside the coaxial tube 66 in the radial direction and not interfering with the slot pairs 54a and 54b.
- a waveguide passage region (mesh) 54c can be provided.
- the optical monitor device 100 transmits the short wavelength light (especially ultraviolet rays) through the portions 52a and 56a through which the monitoring optical waveguide 104 passes in the dielectric window 52 and the dielectric plate 56. Since it is made of synthetic quartz having a high rate, for example, the accuracy of film thickness monitoring using non-coherent monitor light LB and reflected light HB including a wide range of multiple wavelengths of 185 nm to 785 nm is further improved.
- FIG. 5 shows the wavelength dependence of the light transmittance of synthetic quartz and fused silica.
- the light transmittance of fused silica is 90% or more in the wavelength region of 270 nm or more, but decreases when the wavelength is shorter than 270 nm, and particularly significantly (lower than 50%) when the wavelength is shorter than 200 nm.
- the light transmittance of synthetic quartz is within the range of 85% to 92% over the entire wavelength region (185 nm to 785 nm) of the monitor light LB and the reflected light HB, and the homogeneity is high. stable.
- the difficulty with synthetic quartz is its high price.
- synthetic quartz is locally used only in the portions 52a and 56a through which the monitoring optical waveguide 104 passes.
- the dielectric window 52 having a large thickness (volume) does not increase in cost because the remaining most part 52b excluding the region 52a of the optical waveguide 104 is made of inexpensive fused silica. The same applies to the dielectric plate 56.
- the boundary between the fused silica portion 52b and the synthetic quartz portion 52a may be vacuum-sealed by welding, for example. Since the dielectric plate 56 does not need to be vacuum-sealed, synthetic quartz having a diameter of the optical waveguide 104 in a circular hole formed in the fused silica plate 56b for passing the optical waveguide 104 for monitoring. The small disk 56a may be simply fitted.
- FIG. 6 shows a configuration example in the monitor main body 108.
- the optical monitor device 100 in this embodiment includes a light source 130, a light receiving unit 132, and a monitor circuit 134 in the monitor main body 108 in order to monitor the film thickness of the film to be processed on the surface of the semiconductor wafer W in-situ. .
- the light source 130 has, for example, a halogen lamp or a xenon lamp, and generates monitor light LB having multiple wavelengths in the region of at least 185 nm to 785 nm.
- the light source 130 is optically coupled to the forward cable 106a of the optical fiber 106 via an optical lens (not shown), and is turned on (turned on) / off (turned off) in accordance with a control signal RSa from the control unit 94.
- the light receiving unit 132 has a photoelectric conversion element such as a photodiode, for example, and reflects the reflected light HB from the surface of the semiconductor wafer W sent through the return cable 106b of the optical fiber 106 in a number of spectra in the 185 nm to 785 nm region.
- a photoelectric conversion element such as a photodiode, for example, and reflects the reflected light HB from the surface of the semiconductor wafer W sent through the return cable 106b of the optical fiber 106 in a number of spectra in the 185 nm to 785 nm region.
- the monitor circuit 134 includes a reference setting unit 136, a comparison determination unit 138, and a monitor output unit 140.
- the reference setting unit 136 supplies the monitoring reference value or reference data R HB included in the various setting values RSb supplied from the control unit 94 to the comparison determination unit 138.
- the reference data R HB gives a set value or a reference value for a predetermined attribute of the spectrum reflectance signal S HB obtained from the light receiving unit 132.
- the comparison determination unit 138 compares (collates) the spectral reflectance signal S HB received from the light receiving unit 132 with the reference data R HB, and a value or characteristic of a predetermined attribute matches or approximates between the two S HB and R HB. Then, monitor information or a monitor result indicating that the film thickness of the film to be processed on the surface of the semiconductor wafer W has reached the set value (or pre-read and reaches the set value after a predetermined time) is output. Then, a monitor signal MS to that effect is output from the monitor output unit 140, and the control unit 94 (FIG. 1) stops or switches the etching process in response to the monitor signal MS.
- etching process that can suitably apply the film thickness monitoring function of the optical monitoring apparatus 100 in this embodiment, for example, in the manufacturing process of a MOS transistor, a sidewall is formed for an LDD (Lightly Doped Drain) structure or an ultra-shallow junction structure. There is an etch back process for this purpose.
- LDD Lightly Doped Drain
- ultra-shallow junction structure There is an etch back process for this purpose.
- FIG. 7 shows the procedure of the etch-back process in this embodiment.
- an SiO 2 film 142 is formed on the surface of the semiconductor wafer W by a CVD (Chemical Vapor Deposition) method.
- the thin film 144 under the gate electrode 146 is a gate insulating film, for example, a thermal oxide film (SiO 2 film) having a thickness of about 5 nm. Impurity ions are implanted into the substrate surface on both sides of the gate electrode 146.
- the film thickness of the remaining film of the SiO 2 film 142 except the side wall portions on the gate electrode 146 and on both sides thereof is set.
- a second etching step for etching the entire surface is set.
- etching with weak anisotropy is performed by the following recipe, for example.
- Etching gas: Ar / CH 2 F 2 360/20 sccm Pressure in chamber: 100mTorr Microwave power: 2000W High frequency power for bias: 75W
- the film thickness setting value TH s is preferably selected to be a small dimension just before the substrate is exposed, for example, 1 nm.
- the optical monitor monitors the timing at which the thickness of the SiO 2 film 142 reaches the set value TH s in the first etching process. It is detected or estimated by the film thickness monitoring function of the apparatus 100, and at this timing, the first etching process is stopped and then the second etching process is started.
- the optical monitor device 100 turns on the light source 130 during the first etching process, and sends the monitor light LB to the semiconductor wafer on the susceptor 12 via the monitor head 102 and the optical waveguide 104. Irradiate the surface of W. Then, the reflected light HB from the surface of the semiconductor wafer W taken in via the optical waveguide 104 and the monitor head 102 is photoelectrically converted using the light receiving unit 132, and further subjected to signal processing of the monitor circuit 134, whereby the surface of the semiconductor wafer W is It is possible to monitor in real time how the thickness of the SiO 2 film 142 decreases with time in the etching process.
- the SiO 2 film on the surface of the semiconductor wafer W is irradiated with the monitor light LB in the region of 185 nm to 785 nm, and the wavelength dependence characteristic of the spectral reflectance of the reflected light HB obtained thereby is the SiO 2 film.
- the characteristic which changes according to the film thickness of is shown.
- the film thickness of the SiO 2 film 142 is based on the reflectance characteristics in a limited wavelength region near 200 nm or based on the reflectance characteristics profile (waveform) in a wide range of wavelengths (185 nm to 785 nm). Can be detected or estimated at a timing when becomes a set value TH s (1 nm).
- the wavelength dependence characteristic of the reflectance in this embodiment shows that the SiO 2 film 142 is completely removed except for the side wall of the gate electrode 146, that is, the substrate (base) is exposed (FIG. 7).
- the reflectance obtained in the state equivalent to (c)) is set to a normalization reference value (1.00). In this way, by setting the reflectance obtained at the base when the thin film to be etched is completely removed as a reference value, even a very thin film thickness of about 1 nm can be monitored with high accuracy.
- the timing at which the second etching process is stopped may use, for example, a timer function, or a known technique (light emission) that detects plasma light by spectroscopy. Monitor).
- the optical waveguide 104 of the optical monitor device 100 can be used as a window for light emission monitoring.
- the optical monitoring device 100 in this embodiment can be used for various forms of film thickness monitoring or other optical monitoring.
- the inner conductor 68 of the coaxial tube 66 constituting the microwave transmission line 58 is formed as a hollow tube, and this hollow tube 68 is used as the central gas supply path of the processing gas supply unit 80. It is also possible.
- a gas discharge port 150 penetrating the center of the radial line slot antenna 55 is provided so as to be continuous with the hollow tube 68.
- the center of the radial line slot antenna 55 is the center of the radial waveguide. Even if the gas discharge through-hole 150 is formed at this location, the uniformity of the electromagnetic wave radiation characteristics of the radial line slot antenna 55 may be affected. In addition, there is no conflict or conflict with the optical monitor device 100.
- part of the processing gas delivered from the processing gas supply source 82 passes through the gas supply pipe 88 as described above from the gas discharge hole 86 on the side wall of the chamber 10 to the chamber 10. Introduced in. Further, another part of the processing gas delivered from the processing gas supply source 82 is introduced into the chamber 10 through the gas supply pipe 152 and the inner conductor 68 of the coaxial pipe 66 through the gas discharge hole 150 at the center of the ceiling.
- the An MFC (mass flow controller) 154 and an opening / closing valve 156 are provided in the middle of the gas supply pipe 152.
- the monitoring optical waveguide 104 provided around the radial line slot antenna 55 is divided into an optical waveguide 104L for the forward path (only for the monitor light LB) and an optical waveguide 104R for the return path (only for the reflected light HB).
- a configuration of division is also possible.
- Synthetic quartz 52a, mesh-shaped through-hole MH, synthetic quartz 56a, and through-hole 72a are individually provided at a position or part through which waveguide 104R passes.
- the optical system (112L, 114L) and the housing 110L are individually addressed to the optical waveguide 104L for the outward path (only for the monitor light LB), and the optical waveguide for the return path (only for the reflected light HB).
- the optical system (112R, 114R) and the housing 110R are individually addressed to 104R.
- the forward cable 106a is attached to the forward housing 110L via the conductor sleeve 116L, and the return cable 106b is coupled to the backward housing 110R via the conductor sleeve 116R.
- purge gas is supplied to the housings 110L and 110R from a common purge gas supply source 122 through separate gas supply pipes 120L and 120R and gas inlets 118L and 118R.
- optical waveguide 104L for the forward path (exclusively for the monitor light LB) and the optical waveguide 104R for the backward path (exclusively for the reflected light HB) may be formed in a V-shape that is slightly inclined with respect to the vertical line.
- the housings 110L and 110R may be separated from each other.
- the monitor head 102 and the monitor main body 108 it is possible to omit the optical fiber 106 and use another optical transmission system such as a mirror.
- the configuration of the microwave discharge mechanism in the microwave plasma processing apparatus of the above embodiment, in particular, the microwave transmission line 58 and the radial line slot antenna 55 are examples, and other types or forms of microwave transmission lines and slot antennas can also be used. It is.
- synthetic quartz having a high light transmittance with respect to a short wavelength is used for the portion 52a through which the monitoring optical waveguide 104 passes in the dielectric window 52.
- fused silica or another transparent dielectric may be used for the optical waveguide passage portion 52a.
- a non-transparent dielectric such as alumina may be used in the dielectric window 52 except for the optical waveguide passage portion 52a.
- the microwave plasma etching apparatus in the above embodiment generates microwave plasma without a magnetic field, there is no need to provide a magnetic field forming mechanism such as a permanent magnet or an electronic coil around the chamber 10, and its simple apparatus configuration and It has become.
- the present invention can also be applied to a plasma processing apparatus that uses electron cyclotron resonance (ECR).
- ECR electron cyclotron resonance
- the present invention is not limited to the microwave plasma etching apparatus in the above embodiment, but can be applied to other microwave plasma processing apparatuses such as plasma CVD, plasma ALD, plasma oxidation, plasma nitridation, plasma doping, and sputtering. It is. Further, the substrate to be processed in the present invention is not limited to a semiconductor wafer, and various substrates for flat panel displays, photomasks, CD substrates, printed substrates, and the like are also possible.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Hardware Design (AREA)
- Manufacturing & Machinery (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Inorganic Chemistry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Pathology (AREA)
- Immunology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Drying Of Semiconductors (AREA)
- Plasma Technology (AREA)
Abstract
Description
エッチングガス: Ar/O2/CH2F2=1000/2/5sccm
チャンバ内の圧力: 20mTorr
マイクロ波パワー: 2000W
バイアス用高周波電力: 120W
エッチングガス: Ar/CH2F2=360/20sccm
チャンバ内の圧力: 100mTorr
マイクロ波パワー: 2000W
バイアス用高周波電力: 75W
12 サセプタ(下部電極)
26 排気装置
30 (RFバイアス用)高周波電源
52 誘電体窓(天板)
52a 合成石英(光導波路通過部分)
54 スロット板
54a,54b スロットペア
54c 光導波路通過領域(メッシュ)
MH メッシュ状透孔
55 ラジアルラインスロットアンテナ
56 誘電体板
58 マイクロ波伝送線路
60 マイクロ波発生器
66 同軸管
72 カバープレート
72a 貫通孔(光導波路通過部分)
80 処理ガス供給部
94 制御部
100 光学モニタ装置
102 モニタヘッド
108 モニタ本体
Claims (22)
- 少なくとも一部に誘電体窓を備えた真空排気可能な処理容器と、
前記処理容器内で被処理基板を保持する基板保持部と、
前記基板に所望のプラズマ処理を施すために、前記処理容器内に所望の処理ガスを供給する処理ガス供給部と、
前記処理容器内にマイクロ波を放射するための1つまたは複数のスロットを有し、前記誘電体窓の上に設けられる導体のスロット板と、
マイクロ波放電による前記処理ガスのプラズマを生成するために、前記スロット板および前記誘電体窓を介して前記処理容器内にマイクロ波を供給するマイクロ波供給部と、
前記スロット板に形成されたメッシュ状の透孔と前記誘電体窓とを介して前記処理容器内の前記基板の表面を光学的に監視または計測する光学モニタ部と
を有するプラズマ処理装置。 - 前記スロット板の前記メッシュ状透孔が分布する領域は、前記スロットと干渉しない位置に設けられる、請求項1に記載のプラズマ処理装置。
- 前記光学モニタ部は、
モニタ光を発生する光源と、
前記モニタ光に対する前記基板からの反射光を電気信号に変換するための受光部と、
前記受光部からの電気信号を所定の信号処理にかけてモニタ情報またはモニタ結果を出力するモニタ回路と、
前記モニタ光を前記スロット板のメッシュ状透孔および前記誘電体窓を介して前記基板保持部上の前記基板の表面に照射し、前記基板の表面からの反射光を前記誘電体窓および前記メッシュ状透孔を介して取り込むモニタヘッドと、
前記光源から前記モニタヘッドまで前記モニタ光を伝送するためのモニタ光伝送部と、
前記モニタヘッドから前記受光部まで前記反射光を伝送するための反射光伝送部と
を有する、請求項1に記載のプラズマ処理装置。 - 前記光学モニタ装置は、前記基板表面の被加工膜の膜厚を監視または計測する、請求項3に記載のプラズマ処理装置。
- 前記モニタ光は、200nm以下の波長を含む、請求項3に記載のプラズマ処理装置。
- 前記モニタ光は、185nm~785nm帯域の波長を含む、請求項5に記載のプラズマ処理装置。
- 前記モニタヘッドは、
前記スロット板の上方に配置された密閉可能な導体からなるハウジングと、
前記ハウジング内で前記モニタ光または前記反射光が通る位置に配置されている所定の光学部品と、
前記ハウジング内にパージングガスを供給するパージングガス供給部と、
前記ハウジング内を排気する排気部と
を有する、請求項3に記載のプラズマ処理装置。 - 前記モニタヘッドと前記誘電窓の間には、前記マイクロ波供給部からのマイクロ波を径方向に伝搬させながらその波長を短くするための誘電体板と前記誘電体板の上方にカバープレートが設けられ、
前記カバープレートにおいて、前記スロット板の前記メッシュ状透孔が分布する領域と重なる位置には、前記モニタヘッドの前記ハウジングと連通する貫通孔が形成されている、
請求項7に記載のプラズマ処理装置。 - 前記パージングガス供給部より前記ハウジング内に供給されたパージングガスは、前記カバープレートの貫通孔を通って前記排気部へ送られる、請求項8に記載のプラズマ処理装置。
- 前記スロット板の前記メッシュ状透孔が分布する領域の遮光部の上面が丸められている、請求項1に記載のプラズマ処理装置。
- 前記メッシュ状透孔の遮光部の上面はウエットエッチングによって丸められている、請求項10に記載のプラズマ処理装置。
- 前記スロット板の前記メッシュ状透孔が分布する領域の開口率は70%以上である、請求項1に記載のプラズマ処理装置。
- 前記メッシュ状透孔は多角形の開口形状を有する、請求項1に記載のプラズマ処理装置。
- 前記メッシュ状透孔はハニカム構造を有する、請求項13に記載のプラズマ処理装置。
- 前記スロット板は、ラジアルラインスロットアンテナを構成する、請求項1に記載のプラズマ処理装置。
- 前記誘電体窓において、前記スロット板の前記メッシュ状透孔が分布する領域と重なる部分は少なくとも合成石英からなる、請求項1に記載のプラズマ処理装置。
- 前記誘電体窓において、前記スロット板の前記メッシュ状透孔が分布する領域と重ならない部分は溶融石英からなる、請求項16に記載のプラズマ処理装置。
- 前記誘電体板において、前記スロット板の前記メッシュ状透孔が分布する領域と重なる部分は少なくとも合成石英からなる、請求項8に記載のプラズマ処理装置。
- 少なくとも一部に誘電体窓を備えた真空排気可能な処理容器内に被処理基板を収容し、前記処理容器内に処理ガスを供給するとともに、前記誘電体窓の上に設けられた1つまたは複数のスロットを有する導体のスロット板と前記誘電体窓とを介してマイクロ波を前記処理容器内に供給して、マイクロ波放電による前記処理ガスのプラズマを生成し、前記プラズマの下で前記基板に所望のプラズマ処理を施すプラズマ処理装置において、前記基板の表面を光学的に監視または測定するための光学モニタ装置であって、
モニタ光を発生する光源と、
前記モニタ光に対する前記基板からの反射光を電気信号に変換するための受光部と、
前記受光部からの電気信号を所定の信号処理にかけてモニタ情報またはモニタ結果を出力するモニタ回路と、
前記モニタ光と前記基板の表面からの反射光とを通すために前記スロット板に形成されたメッシュ状の透孔と、
前記モニタ光を前記スロット板のメッシュ状透孔および前記誘電体窓を介して前記基板保持部上の前記基板の表面に照射し、前記基板の表面からの反射光を前記誘電体窓および前記スロット板のメッシュ状透孔を介して取り込むモニタヘッドと、
前記光源から前記モニタヘッドまで前記モニタ光を伝送するためのモニタ光伝送部と、
前記モニタヘッドから前記受光部まで前記反射光を伝送するための反射光伝送部と
を有する光学モニタ装置。 - 前記スロット板には、前記モニタ光を通すための第1のメッシュ状透孔と、前記基板の表面からの反射光を通すための第2のメッシュ状透孔とが形成され、
前記モニタヘッドは、前記モニタ光を前記スロット板の前記第1のメッシュ状透孔および前記誘電体窓を介して前記基板保持部上の前記基板の表面に照射し、前記基板の表面からの反射光を前記誘電体窓および前記スロット板の前記第2のメッシュ状透孔を介して取り込む、
請求項19に記載の光学モニタ装置。 - 前記モニタヘッドは、
密閉可能な導体からなるハウジングと、
前記ハウジング内で前記モニタ光または前記反射光が通過する位置に配置されている光学部品と、
前記ハウジング内にパージングガスを供給するパージングガス供給部と、
前記ハウジング内を排気する排気部と
を有する、請求項19に記載の光学モニタ装置。 - 少なくとも一部に誘電体窓を備えた真空排気可能な処理容器内に被処理基板を収容し、前記処理容器内に処理ガスを供給するとともに、前記処理容器内にエネルギーを供給して、前記エネルギーを用いて前記処理ガスのプラズマを生成し、前記プラズマの下で光学モニタ装置から得られた信号に基づき前記基板に所望のプラズマ処理を施すプラズマ処理装置であって、
前記光学モニタ装置は、
モニタ光を発生する光源と、
前記モニタ光に対する前記基板からの反射光を電気信号に変換するための受光部と、
前記受光部からの電気信号を所定の信号処理にかけてモニタ情報またはモニタ結果を出力するモニタ回路と、
前記モニタ光を前記基板保持部上の前記基板の表面に照射し、前記基板の表面からの反射光を取り込むモニタヘッドと、
前記光源から前記モニタヘッドまで前記モニタ光を伝送するためのモニタ光伝送部と、
前記モニタヘッドから前記受光部まで前記反射光を伝送するための反射光伝送部と
を有し、
前記モニタヘッドは、
前記処理容器に配置された密閉可能なハウジングと、
前記ハウジング内にパージングガスを供給するパージングガス供給部と、
前記ハウジング内を排気する排気部と
を有するプラズマ処理装置。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/818,720 US8974628B2 (en) | 2010-08-26 | 2011-08-24 | Plasma treatment device and optical monitor device |
CN2011800414514A CN103069551A (zh) | 2010-08-26 | 2011-08-24 | 等离子体处理装置和光学监视装置 |
KR1020137006702A KR101378693B1 (ko) | 2010-08-26 | 2011-08-24 | 플라즈마 처리 장치 및 광학 모니터 장치 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010-189435 | 2010-08-26 | ||
JP2010189435A JP5385875B2 (ja) | 2010-08-26 | 2010-08-26 | プラズマ処理装置及び光学モニタ装置 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012026117A1 true WO2012026117A1 (ja) | 2012-03-01 |
Family
ID=45723139
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2011/004698 WO2012026117A1 (ja) | 2010-08-26 | 2011-08-24 | プラズマ処理装置及び光学モニタ装置 |
Country Status (6)
Country | Link |
---|---|
US (1) | US8974628B2 (ja) |
JP (1) | JP5385875B2 (ja) |
KR (1) | KR101378693B1 (ja) |
CN (1) | CN103069551A (ja) |
TW (1) | TWI437634B (ja) |
WO (1) | WO2012026117A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104347338A (zh) * | 2013-08-01 | 2015-02-11 | 中微半导体设备(上海)有限公司 | 等离子体处理装置的冷却液处理系统及方法 |
AT517982A1 (de) * | 2015-12-07 | 2017-06-15 | Universität Linz | Vorrichtung zur Abgasanalyse einer Verbrennungskraftmaschine |
TWI618140B (zh) * | 2015-12-31 | 2018-03-11 | Advanced Micro Fab Equip Inc | Inductively coupled plasma processor |
Families Citing this family (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010016225A (ja) * | 2008-07-04 | 2010-01-21 | Tokyo Electron Ltd | 温度調節機構および温度調節機構を用いた半導体製造装置 |
DE102010027224A1 (de) * | 2010-07-15 | 2012-01-19 | Forschungszentrum Jülich GmbH | Elektrode zur Erzeugung eines Plasmas, Plasmakammer mit dieser Elektrode und Verfahren zur in situ-Analyse oder -in situ-Bearbeitung einer Schicht oder des Plasmas |
US9134257B2 (en) * | 2013-03-14 | 2015-09-15 | Graphic Packaging International, Inc. | Method and apparatus for identifying defects in susceptors of microwave food containers |
US9867269B2 (en) * | 2013-03-15 | 2018-01-09 | Starfire Industries, Llc | Scalable multi-role surface-wave plasma generator |
CN103515486A (zh) * | 2013-10-25 | 2014-01-15 | 浙江光普太阳能科技有限公司 | 一种板式pecvd制备背面点接触太阳能电池的方法 |
CN103646840A (zh) * | 2013-11-29 | 2014-03-19 | 上海华力微电子有限公司 | 用于离子注入机预冷腔的晶片固定装置 |
KR102108318B1 (ko) * | 2013-12-23 | 2020-05-11 | 세메스 주식회사 | 기판 처리 장치 |
JP6366383B2 (ja) * | 2014-06-27 | 2018-08-01 | 株式会社ディスコ | 加工装置 |
JP2016092102A (ja) * | 2014-10-31 | 2016-05-23 | 東京エレクトロン株式会社 | 有機膜をエッチングする方法 |
KR20180042400A (ko) * | 2016-09-20 | 2018-04-25 | 루마센스 테크놀로지스 홀딩스, 인코포레이티드 | 온도 프로브 |
US11022877B2 (en) * | 2017-03-13 | 2021-06-01 | Applied Materials, Inc. | Etch processing system having reflective endpoint detection |
KR20190005029A (ko) * | 2017-07-05 | 2019-01-15 | 삼성전자주식회사 | 플라즈마 처리 장치 |
KR101893035B1 (ko) * | 2017-09-27 | 2018-08-30 | 비씨엔씨 주식회사 | 플라즈마 공정 챔버의 커버링 어셈블리 |
CN108018536A (zh) * | 2017-11-10 | 2018-05-11 | 上海华力微电子有限公司 | 物理气相沉积设备以及方法 |
US11437224B2 (en) * | 2019-09-09 | 2022-09-06 | Shibaura Mechatronics Corporation | Plasma processing apparatus |
US11557825B2 (en) | 2019-10-15 | 2023-01-17 | Huawei Technologies Co., Ltd. | Antenna integrated display screen |
CN110850690B (zh) * | 2019-11-19 | 2023-05-23 | 上海华力微电子有限公司 | 去胶设备、顶针监控方法和去胶工艺 |
JP7479207B2 (ja) * | 2020-06-09 | 2024-05-08 | 東京エレクトロン株式会社 | エッチング方法及び基板処理装置 |
JP7458292B2 (ja) * | 2020-10-20 | 2024-03-29 | 東京エレクトロン株式会社 | プラズマ処理装置 |
KR102543670B1 (ko) * | 2020-11-30 | 2023-06-16 | 주식회사 더웨이브톡 | 탁도계 |
KR20230033984A (ko) * | 2021-09-02 | 2023-03-09 | 주식회사 원익아이피에스 | 기판처리장치 |
JP2024017373A (ja) * | 2022-07-27 | 2024-02-08 | 日新電機株式会社 | プラズマ処理装置 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004518272A (ja) * | 2000-10-23 | 2004-06-17 | アプライド マテリアルズ インコーポレイテッド | 反射放射線を用いる基板処理の監視 |
JP2007067423A (ja) * | 2006-09-29 | 2007-03-15 | Toshiba Corp | 光学式プロセスモニタ装置、光学式プロセスモニタ方法及び半導体装置の製造方法 |
JP2008251660A (ja) * | 2007-03-29 | 2008-10-16 | Tokyo Electron Ltd | プラズマ処理装置 |
JP2010034393A (ja) * | 2008-07-30 | 2010-02-12 | Tokyo Electron Ltd | 基板処理制御方法及び記憶媒体 |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3376921D1 (en) * | 1982-09-10 | 1988-07-07 | Nippon Telegraph & Telephone | Ion shower apparatus |
US6390019B1 (en) * | 1998-06-11 | 2002-05-21 | Applied Materials, Inc. | Chamber having improved process monitoring window |
US6870123B2 (en) * | 1998-10-29 | 2005-03-22 | Canon Kabushiki Kaisha | Microwave applicator, plasma processing apparatus having same, and plasma processing method |
TW580735B (en) * | 2000-02-21 | 2004-03-21 | Hitachi Ltd | Plasma treatment apparatus and treating method of sample material |
US6831742B1 (en) | 2000-10-23 | 2004-12-14 | Applied Materials, Inc | Monitoring substrate processing using reflected radiation |
JP3735329B2 (ja) | 2002-08-22 | 2006-01-18 | 三菱重工業株式会社 | マイクロ波励起放電ランプ |
US7033518B2 (en) * | 2003-06-24 | 2006-04-25 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method and system for processing multi-layer films |
US20060075968A1 (en) * | 2004-10-12 | 2006-04-13 | Applied Materials, Inc. | Leak detector and process gas monitor |
JP4718189B2 (ja) | 2005-01-07 | 2011-07-06 | 東京エレクトロン株式会社 | プラズマ処理方法 |
US7537671B2 (en) * | 2006-09-29 | 2009-05-26 | Tokyo Electron Limited | Self-calibrating optical emission spectroscopy for plasma monitoring |
CN101647101B (zh) | 2007-03-29 | 2012-06-20 | 东京毅力科创株式会社 | 等离子加工设备 |
JP5058084B2 (ja) | 2007-07-27 | 2012-10-24 | 株式会社半導体エネルギー研究所 | 光電変換装置の作製方法及びマイクロ波プラズマcvd装置 |
JP2009054818A (ja) | 2007-08-28 | 2009-03-12 | Tokyo Electron Ltd | プラズマ処理装置、プラズマ処理方法および終点検出方法 |
JP5149610B2 (ja) * | 2007-12-19 | 2013-02-20 | 株式会社日立ハイテクノロジーズ | プラズマ処理装置 |
-
2010
- 2010-08-26 JP JP2010189435A patent/JP5385875B2/ja not_active Expired - Fee Related
-
2011
- 2011-08-24 KR KR1020137006702A patent/KR101378693B1/ko active IP Right Grant
- 2011-08-24 US US13/818,720 patent/US8974628B2/en not_active Expired - Fee Related
- 2011-08-24 CN CN2011800414514A patent/CN103069551A/zh active Pending
- 2011-08-24 WO PCT/JP2011/004698 patent/WO2012026117A1/ja active Application Filing
- 2011-08-25 TW TW100130476A patent/TWI437634B/zh not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004518272A (ja) * | 2000-10-23 | 2004-06-17 | アプライド マテリアルズ インコーポレイテッド | 反射放射線を用いる基板処理の監視 |
JP2007067423A (ja) * | 2006-09-29 | 2007-03-15 | Toshiba Corp | 光学式プロセスモニタ装置、光学式プロセスモニタ方法及び半導体装置の製造方法 |
JP2008251660A (ja) * | 2007-03-29 | 2008-10-16 | Tokyo Electron Ltd | プラズマ処理装置 |
JP2010034393A (ja) * | 2008-07-30 | 2010-02-12 | Tokyo Electron Ltd | 基板処理制御方法及び記憶媒体 |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104347338A (zh) * | 2013-08-01 | 2015-02-11 | 中微半导体设备(上海)有限公司 | 等离子体处理装置的冷却液处理系统及方法 |
AT517982A1 (de) * | 2015-12-07 | 2017-06-15 | Universität Linz | Vorrichtung zur Abgasanalyse einer Verbrennungskraftmaschine |
AT517982B1 (de) * | 2015-12-07 | 2017-11-15 | Universität Linz | Vorrichtung zur Abgasanalyse einer Verbrennungskraftmaschine |
TWI618140B (zh) * | 2015-12-31 | 2018-03-11 | Advanced Micro Fab Equip Inc | Inductively coupled plasma processor |
Also Published As
Publication number | Publication date |
---|---|
CN103069551A (zh) | 2013-04-24 |
JP2012049299A (ja) | 2012-03-08 |
TWI437634B (zh) | 2014-05-11 |
JP5385875B2 (ja) | 2014-01-08 |
KR20130136451A (ko) | 2013-12-12 |
US8974628B2 (en) | 2015-03-10 |
KR101378693B1 (ko) | 2014-03-27 |
US20130180660A1 (en) | 2013-07-18 |
TW201230188A (en) | 2012-07-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5385875B2 (ja) | プラズマ処理装置及び光学モニタ装置 | |
US10734197B2 (en) | Plasma process apparatus | |
KR100886473B1 (ko) | 플라즈마 처리 방법 | |
JP4553995B2 (ja) | リモートマイクロ波プラズマ装置 | |
JP4777717B2 (ja) | 成膜方法、プラズマ処理装置および記録媒体 | |
JP2006128000A (ja) | プラズマ処理装置 | |
JPWO2008026531A1 (ja) | プラズマ酸化処理方法 | |
JP2006244891A (ja) | マイクロ波プラズマ処理装置 | |
JP4504511B2 (ja) | プラズマ処理装置 | |
JP2570090B2 (ja) | ドライエッチング装置 | |
JP5522887B2 (ja) | プラズマ処理装置 | |
JP5700032B2 (ja) | プラズマドーピング装置、およびプラズマドーピング方法 | |
TW201415549A (zh) | 電漿處理裝置及電漿處理方法 | |
JP2001167900A (ja) | プラズマ処理装置 | |
JP4261236B2 (ja) | マイクロ波プラズマ処理装置および処理方法 | |
TWI423336B (zh) | 半導體元件及其製造方法,以及製造半導體元件之裝置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201180041451.4 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11819593 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 20137006702 Country of ref document: KR Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13818720 Country of ref document: US |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 11819593 Country of ref document: EP Kind code of ref document: A1 |