Plasma processing apparatus
A plasma processing apparatus comprises a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed, an evacuation system coupled to the processing vessel, a plasma gas supply part for supplying plasma gas to an interior of the processing vessel, a microwave antenna provided on the processing vessel in correspondence to the substrate to be processed, and a process gas supply part provided between the substrate to be processed on the stage and the plasma gas supply part so as to face the substrate to be processed on the stage, wherein the process gas supply part comprises a plurality of first apertures for passing through plasma formed in the interior of the processing vessel, a process gas passage capable of connecting to a process gas source, a plurality of second apertures in communication with the process gas passage and a diffusion part provided opposite to the second aperture for diffusing process gas released from the second aperture.
This application is a divisional of application Ser. No. 10/276,673, filed Nov. 18, 2002, which is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-094272, filed Mar. 28, 2001; and PCT International Application No. PCT/JP02/03108, filed Mar. 28, 2002, the entire contents of both of which are incorporated by herein by reference.
TECHNICAL FIELDThe present invention generally related to plasma processing apparatus and more particularly to a microwave plasma processing apparatus.
Plasma process and plasma processing apparatus are indispensable technology for fabricating ultrafine semiconductor devices of these days called deep submicron devices or deep subquarter micron devices characterized by a gate length of near 0.1 μm or less, or for fabricating ultra high-resolution flat-panel display devices including liquid crystal display devices.
Conventionally, various plasma excitation methods have been used in plasma processing apparatuses used for fabrication of semiconductor devices or liquid crystal display devices. Particularly, a parallel-plate type high-frequency excitation plasma processing apparatus or an induction-coupled plasma processing apparatus are used commonly. However, such conventional plasma processing apparatuses have a drawback of non-uniform plasma formation in that the region of high electron density is limited, and it has been difficult to conduct a uniform process high electron density is limited, and it has been difficult to conduct a uniform process over the entire substrate surface with large processing rate, and hence with large throughput. This problem becomes particularly acute when processing a large diameter substrate. Further, such a conventional plasma processing device has several inherent problems, associated with its high electron temperature, in that the semiconductor devices formed on the substrate undergo damaging and that significant metal contamination is caused as a result of sputtering of a chamber wall. Thus, there are increasing difficulties in such conventional plasma processing apparatuses to meet for the stringent demand of further device miniaturization and further improvement of productivity of semiconductor devices or liquid crystal display devices.
Meanwhile, there are proposals of a microwave plasma processing apparatus that uses high-density plasma excited by a microwave electric field, in place of a direct-current magnetic field. For example, there is a proposal of a plasma processing apparatus that causes excitation of plasma by radiating a microwave into a processing vessel from a planar antenna (radial line slot antenna) having a number of slots disposed so as to form a uniform microwave, such that the microwave electric field causes ionization of a gas in a vacuum vessel. (See for example Japanese Laid-Open Patent Application 9-63793). In the microwave plasma thus excited, it is possible to realize a high plasma density over a wide area right underneath the antenna, and it becomes possible to conduct uniform plasma processing in a short duration. The microwave plasma thus formed is characterized by low electron temperature, and damaging or metal contamination of the substrate is avoided. Further, it is possible to form uniform plasma over a large surface area, and it can be easily applied to the fabrication process of a semiconductor device using a large diameter semiconductor substrate or large size liquid crystal display device.
BACKGROUND ART
Referring to
On the processing chamber 101, there is formed a plate 103 of plate-like form at the location corresponding to the substrate 114 on the stage 115 as a part of the outer wall of the processing chamber 101 via a seal ring 109, wherein the shower plate 103 is formed of a dielectric material of small loss and includes a large number of apertures 107. Further, a cover plate 102 also of a dielectric material of small loss is provided on the outer side of the shower plate 103 via another seal ring 108.
The shower plate 103 is formed with a passage 104 of a plasma gas on the top surface thereof, and each of the plural apertures 107 are formed in communication with the foregoing plasma gas passage 104. Further, there is formed a plasma gas supply passage 106 in the interior of the shower plate 103 in communication with a plasma gas supply port 105 provided on the outer wall of the processing vessel 101. Thus, the plasma gas of Ar, Kr or the like supplied to the foregoing plasma gas supply port 105 is supplied to the foregoing apertures 107 from the supply passage 106 via the passage 104 and is released into a space 101B right underneath the shower plate 103 in the processing vessel 101 from the apertures 107 with substantially uniform concentration.
On the processing vessel 101, there is provided a radial line slot antenna 110 having a radiation surface shown in
The radial line slot antenna 110 is formed of a flat disk-like antenna body 110B connected to an outer waveguide of the coaxial waveguide 110A and a radiation plate 110C is provided on the mouth of the antenna body 110B, wherein the radiation plate 110C is formed with a number of slots 110a and slots 110b wherein slots 110b are formed in a direction crossing the slots 110a perpendicularly as represented in
In the radial line slot antenna 110 of such a construction, the microwave supplied from the coaxial waveguide 110 spreads between the disk-like antenna body 110B and the radiation plate 110C as it is propagated in the radial direction, wherein there occurs a compression of wavelength as a result of the action of the retardation plate 110D. Thus, by forming the slots 110a and 110b in concentric relationship in correspondence to the wavelength of the radially propagating microwave so as to cross perpendicularly with each other, it becomes possible to emit a plane wave having a circular polarization state in a direction substantially perpendicular to the radiation plate 110C.
By using such a radial line slot antenna 110, uniform plasma is formed in the space 101B right underneath the shower plate 103. The high-density plasma thus formed is characterized by a low electron temperature and thus, there is caused no damaging of the substrate 114 and there is caused no metal contamination as a result of the sputtering of the vessel wall of the processing vessel 101.
In the plasma processing apparatus of
Thus, in the case a processing gas is released into the space 101C from the conductive structure 111 via the nozzles 113, the processing gas is excited by the high-density plasma formed in the space 101B and a uniform plasma processing is conducted on the substrate 114 efficiently and with high rate, without damaging the substrate or the devices on the substrate, and without contaminating the substrate. Further, it should be noted that the microwave emitted from the radial line slot antenna is blocked by the conductive structure and there is no possibility of such a microwave causes damaging in the substrate 114.
Meanwhile, in the plasma processing apparatus 100 mentioned in
Referring to
According to the construction, a process gas is released almost uniformly from a number of the nozzle apertures 113 to a surface of the substrate 114 to be processed represented in
Furthermore, the plasma processing apparatus 100 in
Accordingly, it is an object of the present invention to provide a novel and useful plasma processing apparatus in which the foregoing problems are eliminated.
Another and more specific object of the present invention is to provide a plasma processing apparatus comprising a process gas supply part capable of supplying a process gas uniformly.
Another object of the present invention is to provide a plasma processing apparatus capable of avoiding a rise in temperature thereof.
Another object of the present invention is to provide a plasma processing apparatus, comprising: a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed on the stage; an evacuation system coupled to the processing vessel; a plasma gas supply part for supplying plasma gas to an interior of the processing vessel; a microwave antenna provided on the processing vessel in correspondence to the substrate to be processed on the stage; and a process gas supply part provided between the substrate to be processed on the stage and the plasma gas supply part so as to face the substrate to be processed, wherein the process gas supply part comprises a plurality of first apertures for passing through plasma formed in the interior of the processing vessel, a process gas passage capable of connecting to a process gas source, a plurality of second apertures in communication with the process gas passage and a diffusion part provided opposite to the second aperture for diffusing process gas released from the second aperture.
According to the present invention, in the process gas supply part, there is provided the diffusion part corresponding to a nozzle aperture releasing the process gas, thereby curving a flow of the process gas in a lateral direction and facilitating diffusion and mixture of the process gas. At the time, if the process gas supply part comprises a first part having the process gas passage and the nozzle aperture and a second part having the diffusion part, it becomes possible to form easily the diffusion part in a depression form corresponding to the nozzle aperture. When such a diffusion part is provided at both sides of a nozzle aperture to pass through plasma alternately, the diffusion part makes it possible to further curve the flow of the process gas that has been curved in the lateral direction, thereby further facilitating diffusion and mixture of the process gas. Also, the first part and the second part are formed of different members and there is provided a coolant passage in the second part. As a result, it is possible to suppress a rise in temperature of the process gas supply part.
Another object of the present invention is to provide a plasma processing apparatus, comprising: a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed; an evacuation system coupled to the processing vessel; a plasma gas supply part for supplying plasma gas to an interior of the processing vessel; a microwave antenna provided on the processing vessel in correspondence to the substrate to be processed on the stage; and a process gas supply part provided between the substrate to be processed on the stage and the plasma gas supply part so as to face the substrate to be processed on the stage, wherein the process gas supply part comprises a plurality of first apertures for passing through plasma formed in the interior of the processing vessel, a process gas passage capable of connecting to a process gas source, and a plurality of second apertures in communication with the process gas passage, the second aperture releasing the process gas in a slanting direction with respect to the substrate to be processed.
According to the present invention, the process gas supplied from the process gas supply part bounces on a surface of the substrate to be processed, thereby reaching a microwave window and the process gas supply part. As a result, it becomes possible to avoid the problem that deposition arises.
Another object of the present invention is to provide a plasma processing apparatus, comprising: a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed; an evacuation system coupled to the processing vessel; a plasma gas supply part for supplying plasma gas to an interior of the processing vessel; a microwave window provided on a part of the outer wall of the processing vessel so as to face the substrate to be processed on the stage, the microwave window being formed of a dielectric material; a microwave antenna coupled to the microwave window; a process gas supply part provided between the substrate to be processed on the stage and the plasma gas supply part so as to face the substrate to be processed on the stage; and a temperature control part controlling a surface temperature of the microwave window around 150° C. with respect to a side faced on the substrate to be processed.
According to the present invention, the temperature control of the microwave window around 150° C. suppresses formation of deposition on a surface of the microwave window.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Hereinafter, the present invention will be described in detail with reference to embodiments.
[First Embodiment]
Referring to
The processing vessel 11 is preferably formed of an austenite stainless steel containing Al, and there is formed a protective film of aluminum oxide on the inner wall surface by an oxidizing process. Further, there is formed a disk-like shower plate 14 of dense Al2O3, formed by a HIP process, in the part of the outer wall of the processing vessel 11 corresponding to the substrate 12 as a part of the outer wall, wherein the shower plate 14 includes a large number of nozzle apertures 14A. The Al2O3 shower plate 14 thus formed by a HIP process is formed by using an Y2O3 additive and has porosity of 0.03% or less. This means that the Al2O3 shower plate is substantially free from pores or pinholes and has a very large, while not so large as that of AlN, thermal conductivity for a ceramic of 30 W/m·K.
The shower plate 14 is mounted on the processing vessel 11 via a seal ring 11s, and a cover plate 15 of dense Al2O3 formed also of an HIP process is provided on the shower plate 14 via a seal ring 11t. The shower plate 14 is formed with a depression 14B communicating with each of the nozzle apertures 14A and serving for the plasma gas passage, at the side thereof contacting with the cover plate 15, wherein the depression 14B also communicates with another plasma gas passage 14C formed in the interior of the shower plate 14 in communication with a plasma gas inlet 11p formed on the outer wall of the processing vessel 11.
The shower plate 14 is held by an extending part lib formed on the inner wall of the processing vessel 11, wherein the extending part 11b is formed with a round surface at the part holding the shower plate 14 so as to suppress electric discharge.
Thus, the plasma gas such as Ar or Kr supplied to the plasma gas inlet 11p is supplied to a space 11 B right underneath the shower plate 14 uniformly via the apertures 14A after being passed through the passages 14C and 14B in the shower plate 14.
On the cover plate 15, there is provided a radial line slot antenna 20 formed of a disk-like slot plate 16 formed with a number of slots 16a and 16b shown in
In order to improve intimate contact between the radial line slot antenna 20 and the cover plate 15, the microwave plasma processing apparatus 10 of the present embodiment has a ring-shaped groove 15g on a part of the processing vessel 11 so as to engage with the slot plate 16. By evacuating the groove 15g via an evacuation port 11G communicating therewith, the pressure in the gap formed between the slot plate 16 and the cover plate 15 is reduced and the radial line slot antenna 20 is urged firmly upon the cover plate 15 by the atmospheric pressure. It should be noted that such a gap includes not only the slots 16a and 16b formed in the slot plate 16 but also a gap formed by other various reasons. It should be noted further that such a gap is sealed by the seal ring 11u provided between the radial line slot antenna 20 and the processing vessel 11.
By filling the gap between the slot plate 16 and the cover plate 15 with an inert gas of small molecular weight via the evacuation port 11G and the groove 11g, heat transfer from the cover plate 15 to the slot plate 16 is facilitated. Thereby, it is preferable to use He for such an inert gas in view of large thermal conductivity and large ionization energy. In the case the gap is filled with He, it is preferable to set the pressure to about 0.8 atm. In the construction of
It should be noted that an outer waveguide tube 21A of the coaxial waveguide 21A is connected to the disk-like antenna body 17 while a central conductor 21B is connected to the slot plate 16 via an opening formed in the retardation plate 18. Thus, the microwave fed to the coaxial waveguide 21A is propagated in the radial direction between the antenna body 17 and the slot plate 16 and is emitted from the slots 16a and 16b.
Referring to
In the plasma processing apparatus 10 of
In the microwave plasma processing apparatus 10 of
In the microwave plasma processing apparatus 10 of the present embodiment, it is possible to avoid deposition of reaction byproducts on the inner wall of the processing vessel by heating the outer wall of the processing vessel 11 to a temperature of about 150° C. Thereby, the microwave plasma processing apparatus 10 can be operated constantly and with reliability, by merely conducing a dry cleaning process once a day or so.
Referring to
Referring to
Referring to
As shown in
Referring to
As a result, as shown in
Similarly, a flow of a process gas curved laterally by the depression 31F2 hits a portion 31E1 of the lattice-shaped structure 31E in which the depression 31F1 is not formed, thereby curving. A flow of a process gas curved laterally by the depression 31F3 hits a portion 31E4 of the lattice-shaped structure 31E in which the depression 31F4 is not formed, thereby curving. A flow of a process gas curved laterally by the depression 31F4 hits a portion 31E3 of the lattice-shaped structure 31E in which the depression 31F3 is not formed, thereby curving.
As a result of complicated curved flows of the process gas shown in
The lattice-shaped process gas passage 31B and the process gas nozzle apertures 31D are provided to cover a slightly larger range than the substrate 12 represented by a broken line in
In a case that the process gas supply mechanism 31 is formed of a conductive material such as metal, an iterated pitch of the lattice-shaped process gas apertures is set shorter than a wavelength of the foregoing microwave, whereby the process gas supply mechanism 31 forms a surface of short circuit of the microwave. In this case, microwave excitation of plasma occurs only in the space 11B and a process gas is activated in the space 11C including a surface of the substrate 12 by plasma diffusing from the excited space 11B.
The microwave plasma processing apparatus 10 according to this embodiment of the present invention uses the process gas supply mechanism 31 to control the uniform supply of a process gas, thereby eliminating an excessive amount of dissociation of the process gas on the surface of the substrate 12. Even if there is formed a structure of a large aspect ratio on the surface of the substrate 12, it is possible to process a desirable substrate as far as an inner portion of such an aspect structure. Thus, the microwave plasma processing apparatus 10 is useful for fabricating a plurality of generations of semiconductor apparatuses differing in designing rules.
In the plasma processing apparatus 10 according to this embodiment of the present invention, the disk-like conductive members 311 and 312 may be formed of an Al alloy containing Mg or a stainless steel added with Al. When the Al alloy containing Mg is used, it is preferable to form membrane of fluoride on surfaces of the members. On the other hand, when the disk-like conductive members 311 and 312 are formed of the stainless steel added with Al, it is desirable to form insulating membrane of alumina on the surfaces of the members. In the plasma processing apparatus 10 according to the present invention, incident energy is small because of a low electron temperature in the excited plasma, thereby avoiding the problem that metal contamination occurs to the substrate 12 by sputtering of the process gas supply mechanism 31. It should be noted that the process. gas supply mechanism 31 may be formed of a ceramic such as alumina.
Also, in this embodiment of the present invention, it is possible that either of the disk-like conductive members 311 or 312 is formed of a conductive material and the other is formed of an insulator.
[Second Embodiment]
Referring to
In
The structure of
[Third Embodiment]
Referring to
Also in such a plasma processing apparatus 10A, it is possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Fourth Embodiment]
Referring to
Also in such a plasma processing apparatus 10B, it is possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Fifth Embodiment]
Referring to
Also in such a plasma processing apparatus 10C, it becomes possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Sixth Embodiment]
Referring to
In such a plasma processing apparatus 10D, it is possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Seventh Embodiment]
Referring to
In such a plasma processing apparatus 10E, it is possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Eighth Embodiment]
Referring to
In such a plasma processing apparatus 10F, although the slot plate 16 is mounted on the processing vessel 11 via the seal ring lit, it is not necessary to provide a seal ring to seal the edge 21b of the central conductive body 21B toward an air pressure because the edge 21b of the central conductive body 21B is formed behind the retardation plate 18. According to this embodiment of the present invention, it becomes possible to excite efficiently microwave in the processing vessel 11 without loss of the microwave because the slot plate 16 of the radial line slot antenna 20 is exposed to the interior of the processing vessel 11.
Also in such a plasma processing apparatus 10F, it is possible to supply a process gas to the space 11C on the substrate 12 uniformly and with reliability by using the process gas supply mechanism 31 or 41 in
[Ninth Embodiment]
Referring to
Referring to
When the process gas is released in the slanting direction from the process gas supply nozzle apertures 51C to the substrate 12, the released process gas bounces off the substrate 12, thereby avoiding the problem that there is formed deposition of reaction byproducts on a surface of the shower plate 103.
As shown in
[Tenth Embodiment]
A description will be given of a tenth embodiment of the present invention.
According to this embodiment of the present invention, in order to suppress the deposition of reaction byproducts on the surface of the shower plate 103, the foregoing coolant block 19 serves as a temperature control apparatus under a substrate processing apparatus 10 in
As a result of the temperature control of the shower plate 13 or the cover plate 15 around 150° C., even if CVD coating process or plasma etching process is performed in the processing space 11C, it becomes possible to suppress deposition on the surface of the shower plate 13 or the cover plate 15.
On the other hand, when the foregoing temperature is substantially above 150° C., it is likely that process gas supplied from the process gas supply mechanism 31, 41 or 51 is dissolved. Thus, it is preferable to control the temperature of the shower plate 13 or the cover plate 15 less than 150° C.
By letting a medium such as galden in a coolant passage 19A of the coolant block 19, it is possible to control the temperature.
Further, the present invention is not limited to the specific embodiments noted above but various variations and modifications may be made within the scope of the invention set forth in claims.
INDUSTRIAL APPLICABILITYAccording to the present invention, in a microwave plasma processing apparatus, it is possible to supply a process gas to an interior of a processing vessel uniformly and perform a uniform plasma process.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Claims
1-17. (canceled)
18. A plasma processing apparatus, comprising:
- a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed;
- an evacuation system coupled to said processing vessel;
- a plasma gas supply part for supplying plasma gas to an interior of said processing vessel;
- a microwave antenna provided on said processing vessel; and
- a process gas supply part provided between said substrate to be processed on said stage and said plasma gas supply part so as to face said substrate to be processed on said stage,
- wherein said process gas supply part comprises: a first component comprising a plurality of first apertures configured to provide flow communication for passing plasma formed in the interior of said processing vessel, a process gas passage capable of connecting to a process gas source, and a plurality of second apertures in flow communication with said process gas passage; and a second component comprising a plurality of third apertures corresponding to and being in substantially axial alignment with said first apertures of said first component and a plurality of diffusion surfaces upon recessed areas of said second component positioned opposite to said second apertures in said first component, wherein said first component and said second component comprise a first member and a second member, respectively, and a coolant passage is provided in said second member.
19. A plasma processing apparatus, comprising:
- a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed;
- an evacuation system coupled to said processing vessel;
- a plasma gas supply part for supplying plasma gas to an interior of said processing vessel;
- a microwave antenna provided on said processing vessel in correspondence to said substrate to be processed on said stage; and
- a process gas supply part provided between said substrate to be processed on said stage and said plasma gas supply part so as to face said substrate to be processed on said stage, wherein said process gas supply part comprises: a first component comprising a plurality of first apertures configured to provide flow communication for passing plasma formed in the interior of said processing vessel, a process gas passage capable of connecting to a process gas source, and a plurality of second apertures in flow communication with said process gas passage; and a second component comprising a plurality of third apertures corresponding to and being in substantially axial alignment with said first apertures of said first component and a plurality of diffusion surfaces upon recessed areas of said second component positioned opposite to said second apertures in said first component, wherein said plurality of second aperture are configured to release said process gas in a slanting direction.
20. A plasma processing apparatus, comprising:
- a processing vessel defined by an outer wall and having a stage for holding a substrate to be processed;
- an evacuation system coupled to said processing vessel; a plasma gas supply part for supplying plasma gas to an interior of said processing vessel;
- a microwave window formed of a dielectric material and provided on a part of said outer wall of said processing vessel so as to face said substrate to be processed on said stage and;
- a microwave antenna coupled to said microwave window;
- a process gas supply part provided between said substrate to be processed on said stage and said plasma gas supply part so as to face said substrate to be processed on said stage; and
- a temperature control part controlling a surface temperature of said microwave window around 150° C. with respect to a side faced on said substrate to be processed on said stage.
21. The microwave plasma processing apparatus as claimed in claim 20, wherein said temperature control part is provided on said microwave antenna and controls a temperature of said microwave window via said microwave antenna.
22. The microwave plasma processing apparatus as claimed in claim 20, wherein said microwave window is a shower plate formed of a dielectric plate forming said plasma gas supply part.
Type: Application
Filed: Jul 18, 2006
Publication Date: Dec 28, 2006
Inventors: Tadahiro Ohmi (Sendai-Shi), Masaki Hirayama (Sendai-Shi), Shigetoshi Sugawa (Sendai-Shi), Tetsuya Goto (Sendai-Shi)
Application Number: 11/488,059
International Classification: C23F 1/00 (20060101); H01L 21/306 (20060101);