Patent Application
20080318431
This invention relates to a shower plate for use in a facility or apparatus for manufacturing a semiconductor device and a semiconductor-related device, in particular, for use in a processing chamber of a plasma processing apparatus, and to a plasma processing apparatus using a shower plate of the type.
In manufacturing processes of a semiconductor and a semiconductor-related device, a process for forming an oxide film, a nitride film, and an oxynitride film on a substrate surface by oxidation, nitridation, and oxynitridation, respectively, or by CVD, and a process for removing these films by etching are executed at various stages. In case where a large amount of products of the same type, such as a general-purpose DRAM, are manufactured, these processes are carried out by processing apparatuses for executing respective unique processes. On the other hand, in case of custom LSI products or the like for which high-mix low-volume production is carried out, it is preferable that a plurality of processes are executed by one or a reduced number of apparatuses, because installation of an expensive processing apparatus for each process is undesirable in view of cost.
In order to execute multifunctional processes in a processing apparatus, there is known a technique of forming an oxide film, a nitride film, and an oxynitride film by causing oxygen radicals and nitrogen radicals excited by plasma to react with a substrate surface or another technique of depositing an oxide film and a nitride film by causing these radicals to react with a silane (SiH4) gas.
Japanese Unexamined Patent Application Publication (JP-A) No. 2002-299331 (patent document) discloses an apparatus of the type. According to the document, a chamber (processing chamber) of the processing apparatus is provided with an upper shower plate made of a dielectric material and adapted to substantially uniformly emit a gas for generating plasma and radicals toward a lower side of the processing chamber, a lower shower plate comprising pipes which have a large number of small apertures adapted to substantially uniformly emit a reactive gas toward a substrate and which are arranged in a lattice pattern so as to form a large number of openings or spaces allowing the plasma or excited radicals from the upper shower plate to pass therethrough, and an antenna for radiating, from a position above the upper shower plate toward the upper shower plate, microwave for generating the plasma. In case where the substrate is oxidized to form an oxide film, an Ar gas, a Kr gas, and an oxygen gas are supplied from the upper shower plate and plasma is generated by microwave. A substrate surface is exposed to oxygen radicals excited there to form the oxide film. Further, in case where a nitride film is deposited by plasma CVD, an Ar gas, a Kr gas, and an ammonia (NH3) gas are supplied to the upper shower plate and plasma is generated by microwave. Nitrogen radicals excited there and a silane (SiH4) gas emitted from the lower shower plate are reacted with each other to deposit a silicon nitride film (Si3N4) on the substrate.
In reactive ion etching, an Ar gas and a Kr gas are introduced from the upper shower plate and plasma is generated by microwave. A CxHy gas as a reactive gas is introduced from the lower shower plate, and a bias voltage is applied to the substrate. Thus, a silicon oxide film on the substrate can be etched.
Patent Document 1: Japanese Unexamined Patent Application Publication (JP-A) No. 2002-299331
The lower shower plate used in the conventional plasma processing apparatus has a structure in which pipes are arranged like a lattice and each pipe has a plurality of nozzles which have the same shape and which are disposed at predetermined intervals. Interior spaces of the pipes are connected to one another to form a passage for a raw material gas to be supplied. A flow rate of the raw material gas from each nozzle is determined by a pressure of the raw material gas at a nozzle inlet corresponding to a nozzle outlet. As long as the pressure of the raw material gas at each nozzle inlet is kept constant, the raw material gas is ejected at a substantially uniform flow rate from the nozzles at both of a center portion and a peripheral portion of the shower plate since the nozzles have the same characteristics.
However, in the conventional shower plate, a flow velocity of the raw material gas is as high as several hundreds m/second to several km/second due to a nozzle structure. Therefore, it is difficult to control a gas flow pattern inside the chamber.
In the conventional shower plate, ejection of the raw material gas is concentrated to an area right under the nozzle and does not spread to a peripheral area around the area right under the nozzle. Therefore, it is difficult to eject the raw material gas with a spread in a transverse direction.
Further, the lower shower plate is disadvantageous as follows. Due to recombination of ions and electrons in plasma, the lower shower plate is elevated in temperature to be mechanically deteriorated or deformed if it is formed of a material easily affected by heat. Even if the material is resistant to heat, deflection or deformation is caused due to nonuniform temperature elevation.
It is therefore an object of the present invention to provide a shower plate for a plasma processing apparatus, which is capable of controlling a gas flow pattern by decreasing a flow velocity of a raw material gas.
It is another object of the present invention to provide a shower plate for a plasma processing apparatus, which is provided with nozzles capable of ejecting a raw material gas with a spatial spread.
It is still another object of the present invention to provide a shower plate for a plasma processing apparatus, which is capable of effectively controlling temperature elevation of the shower plate due to recombination of ions and electrons in plasma.
According to this invention, there is provided a shower plate for a plasma processing apparatus, wherein a plurality of pipe members are disposed with a space portion left between adjacent ones of the pipe members, each of the pipe members defining, within each pipe member, a first gas flow path and a second gas flow path which is coupled to the first gas flow path and which includes a porous material member having a permeability for a process gas.
The second gas flow path has an outwardly convex shape in a sectional plane having a minimum sectional area.
Desirably, the second gas flow path has a thickness in the sectional plane, which is thickened at the center and is decreased toward the periphery.
The porous material member at the center of the second gas flow path may have a porosity different from that of the porous material member at the periphery of the second gas flow path.
Desirably, the pipe member has a refrigerant gas flow path formed therein.
According to this invention, there is provided a shower plate for a plasma processing apparatus wherein a plurality of pipe members are disposed with a space portion left between adjacent ones of the pipe members, each of the pipe members comprising, within each pipe member, a first gas flow path for allowing a predetermined gas to flow therethrough, a second gas flow path connected to the first gas flow path to release the predetermined gas to the outside, and a third gas flow path for allowing a refrigerant gas to flow therethrough.
In this case, it is desired that the first gas flow paths are coupled to one another within the plurality of the pipe members, the third gas flow path being disposed in parallel with the first gas flow path.
Preferably, each pipe member is formed of an alloy containing copper and tungsten.
In this case, it is desired that the alloy of copper and tungsten is an alloy containing 10-20% copper and 90-80% tungsten.
10. The shower plate for a plasma processing apparatus as claimed in any one of claims 1 through 5 and 8 through 9, wherein the porous material member is formed of a number of thin metallic wires.
The thin metallic wire comprises a copper-tungsten alloy.
Desirably, the thin metallic wire is provided with an yttrium oxide coating film.
Desirably, each pipe member has an outer surface coated with an yttrium oxide film.
The pipe members may be disposed circularly or in a lattice pattern.
According to this invention, there is provided a plasma processing apparatus which uses the above-mentioned shower plate for plasma processing.
The shower plate for plasma processing is provided as a lower shower plate.
According to this invention, there is provided a plasma processing method in which a process gas is introduced into a plasma apparatus by using the above-mentioned shower plate and plasma processing is carried out on a substrate.
According to this invention, there is also provided a method of manufacturing an electronic device, the method including the plasma processing mentioned above.
In the shower plate of the present invention, an ejection port for a raw material gas is formed of a porous material. Therefore, it is possible to decrease a flow velocity from the ejection port to thereby create a controlled gas flow pattern.
The shower plate of the present invention has a structure in which the raw material gas is ejected through a porous material member which is formed along a pipe and which has an outwardly convex shape. Therefore, it is possible to eject the raw material gas in a direction of the pipe with a spread in a transverse direction. Thus, the raw material gas can uniformly reach a substrate surface.
Further, in the present invention, a fluid passage for a refrigerant is formed within the pipe along a material gas flow path. Therefore, it is possible to control temperature elevation of the shower plate due to recombination of electrons and ions in plasma. Consequently, the lower shower plate can be prevented from deflection and mechanical deformation. In case where the lower shower plate is made of a material easily affected by heat (for example, an aluminum alloy and so on), deterioration due to heat can be prevented.
Hereinbelow, embodiments of the present invention will be described.
In
Inside the processing chamber (process chamber) 11, a holding stage 13 is disposed which is for holding, by an electrostatic chuck, a substrate 12 to be processed and which is preferably formed of AlN or Al2O3 by hot isostatic pressing (HIP). Inside the processing chamber 11, at least two, preferably three or more exhaust ports 11a are formed in a space 11A surrounding the holding stage 13 at an equal distance, specifically, with a generally axisymmetric relation with respect to the substrate 12 on the holding stage 13. The processing chamber 11 is evacuated and reduced in pressure via the exhaust ports 11a by an irregular pitch irregular inclination screw pump.
On the upper shower plate 14, a cover plate 15 is arranged via a seal ring, which is made of dense Al2O3 and formed by similar HIP processing. The shower plate 14 is provided with a plasma generation gas flow path 14B formed on a side in contact with the cover plate 15 and communicating with each of nozzle apertures 14A. The plasma generation gas flow path 14B is formed inside the shower plate 14 and communicates with another plasma generation gas flow path 14C which communicates with a plasma inlet 11p formed on an outer wall of the processing chamber 11.
The shower plate 14 is held by a protruding portion 11b formed on an inner wall of the processing chamber 11. The protruding portion 11b is provided with roundness (not shown) formed at a part holding the shower plate 14 to suppress abnormal electrical discharge.
A plasma generation gas, such as Ar or Kr, supplied to the plasma inlet 11p successively passes through the flow paths 14C and 14B inside the shower plate 14 and, thereafter, is uniformly supplied to a space 11B right under the shower plate 14 via the apertures 14A.
On the cover plate 15, there is provided a radial line slot antenna 20 comprising a disk-shaped slot plate 16 (see
The radial slot line antenna 20 is mounted on the processing chamber 11 via a seal ring (not shown). The radial line slot antenna 20 is supplied with microwave having a frequency of 2.45 GHz or 8.3 GHz from an external microwave source (not shown) via a coaxial waveguide 21.
The microwave thus supplied is emitted into the interior of the processing chamber 11 from the slots 16a and 16b (see
The coaxial waveguide 21 has an outer waveguide 21A connected to the disk-shaped antenna body 17, and a central conductor 21B connected to the slot plate 16 via an opening or a space portion formed on the retardation plate 18. The microwave supplied to the coaxial waveguide 21A travels in a radial direction between the antenna body 17 and the slot plate 16 and is emitted from the slots 16a and 16b.
Referring to
Referring to
Referring to
Referring to
The circular pipes 31A2 and 31A4 shown in
a) shows a section perpendicular to a drawing sheet and taken along a line AA in
The circular frame pipe 31E has a material gas flow path 31E1 and a refrigerant gas flow path 31E2 formed inside and connected to the material gas flow path 43 and the refrigerant gas flow path 42 of the circular pipes 31A1, 31A2, 31A3, and 31A4 by the coupling pipes 31F1, 31F2, 31F3, and 31F4, respectively.
Further, the circular frame pipe is connected to a material gas supply port 11r and a refrigerant gas supply port 11w through pipes.
A material for the first pipe member of the circular pipe is required to have a sufficiently high thermal conductivity. As a Cu—W alloy used in the present embodiment, an alloy containing 10-20% Cu and 90-80% W is used so as to satisfy the above-mentioned requirement. In this alloy, a thermal conductivity of 80-200 W/m·K is obtained. Further, this alloy has a thermal expansion coefficient of 7 to 8×10−6/K which is approximately equal to a thermal expansion coefficient of 7 to 8×10−6/K of Y2O3. Therefore, as a protection film, the Cu—W alloy can be coated with a thick Y2O3 film. The yttrium oxide film is formed to a thickness of approximately 200 μm by plasma spraying. This Y2O3 film has pores allowing a material gas to pass through.
For the yttrium oxide film, a plasma spraying apparatus has a structure in which an yttria powder raw material is supplied to a plasma generating portion so that the material can be sufficiently melted upon plasma spraying. Thus, the material is sufficiently melted.
As the porous material member 44, it is possible to use a metal filter coated with ceramics. Specifically, the porous material member has a metal filter structure formed by a material comprising thin metallic wires of a copper-tungsten alloy each of which is coated with yttrium oxide (Y2O3). That is, surfaces of pores of the metal filter are coated with yttrium oxide. By selecting a porosity of the metal filter, an ejection flow velocity of the material gas can be controlled. By using such a porous material, the flow velocity of the material gas can be decreased from several tens cm/second to several cm/second to thereby control a gas flow pattern.
Further, as shown in
Furthermore, by varying a material quality of the porous material, it is possible to vary the flow rate of the material gas ejected from each of the circular pipe and to thereby provide a distribution in the flow rate of the material gas. For example, in
In place of the Cu—W alloy, an Al alloy may be used. However, the Al alloy has a thermal expansion coefficient as extremely great as 23×10−6/K. Consequently, there is a possibility of occurrence of cracks in the Y2O3 film as a surface protection film thereof. Therefore, it is required to decrease the thermal expansion coefficient to a level as small as that of the Cu—W alloy, for example, by impregnating silicon carbide (SiC) or carbon (C) fibers with Al. Then, the material must be capable of being subjected to precision machining, such as formation of fine holes in the circular pipe.
A major difference between the second embodiment and the first embodiment is that the circular pipes are concentrically disposed in the first embodiment while, in the present embodiment, the pipes except the circular frame pipe are arranged in a lattice pattern.
Referring to
Referring to
A section taken along a line CC in
As described in the foregoing embodiments, in the lower shower plate of the present invention, the ejection port of the material gas is formed of the porous material member. Therefore, a flow velocity from the ejection port can be decreased to thereby create a controlled gas flow pattern.
As described in the foregoing embodiments, the lower shower plate of the present invention has a structure in which the nozzles are arranged continuously along a direction of the pipe. The material gas can be released with a spread in a transverse direction with respect to a continuing direction of the nozzles. Therefore, a manufacturing apparatus of a semiconductor device and a liquid crystal device, which uses the lower shower plate, can carry out more controlled processing on a substrate.
In the present invention, the refrigerant fluid passage is formed along the material gas flow path within the pipe. Therefore, it is possible to effectively suppress temperature elevation of the shower plate due to recombination of electrons and ions in plasma.
The shower plate according to the present invention is applicable to various types of plasma processing apparatuses and semiconductor manufacturing apparatuses for executing processing, such as CVD and RIE.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-323534 | Nov 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/322136 | 11/7/2006 | WO | 00 | 5/7/2008 |
