Source: http://www.google.com/patents/US6830652?ie=ISO-8859-1&dq=U.S.+Patent+No.+4,528,643
Timestamp: 2015-04-26 02:14:47
Document Index: 712410217

Matched Legal Cases: ['art.\n3', 'art. 4', 'art.\n5', 'art. 6', 'art. 7', 'art. 8', 'art. 9', 'art. 11', 'art. 12', 'art. 13', 'Application No. 9']

Patent US6830652 - Microwave plasma processing apparatus - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsIn a microwave plasma processing apparatus, a metal made lattice-like shower plate 111 is provided between a dielectric material shower plate 103, and a plasma excitation gas mainly an inert gas and a process gas are discharged from different locations. High energy ions can be incident on a surface of...http://www.google.com/patents/US6830652?utm_source=gb-gplus-sharePatent US6830652 - Microwave plasma processing apparatusAdvanced Patent SearchPublication numberUS6830652 B1Publication typeGrantApplication numberUS 09/678,741Publication dateDec 14, 2004Filing dateOct 4, 2000Priority dateMay 26, 1999Fee statusPaidAlso published asEP1115147A1, EP1115147A4, EP1879213A2, EP1879213A3, EP1879213B1, US7520245, US7819082, US20040221809, US20090205782, WO2000074127A1Publication number09678741, 678741, US 6830652 B1, US 6830652B1, US-B1-6830652, US6830652 B1, US6830652B1InventorsTadahiro Ohmi, Masaki HirayamaOriginal AssigneeTokyo Electron Limited, Tadahiro OhmiExport CitationBiBTeX, EndNote, RefManPatent Citations (22), Referenced by (24), Classifications (22), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetMicrowave plasma processing apparatus
US 6830652 B1Abstract
In a microwave plasma processing apparatus, a metal made lattice-like shower plate 111 is provided between a dielectric material shower plate 103, and a plasma excitation gas mainly an inert gas and a process gas are discharged from different locations. High energy ions can be incident on a surface of the substrate 114 by grounding the lattice-like shower plate. The thickness of each of the dielectric material separation wall 102 and the dielectric material at a microwave introducing part is optimized so as to maximize the plasma excitation efficiency, and, at the same time, the distance between the slot antenna 110 and the dielectric material separation wall 102 and a thickness of the dielectric material shower plate 103 are optimized so as to be capable of supplying a microwave having a large power.
What is claimed is: 1. A plasma processing apparatus for applying a process to a substrate to be processed, the plasma processing apparatus comprising:
a chamber of which interior can be depressurized, a gas supply system constructed and arranged to supply a gas to the chamber and an exhaust system configured and arranged to exhaust the gas supplied to the chamber and to depressurize the chamber; a part of a wall constituting the chamber being a flat plate dielectric material plate formed of a material which passes a microwave therethrough substantially without a loss; a flat plate dielectric material shower plate, which is formed of a material which passes a microwave therethrough substantially without a loss, being provided between the dielectric material plate and plasma excited in the chamber; a plurality of gas discharge holes being formed in the dielectric material shower plate so that at least a part of the gas supplied by the gas supply system is discharged through the plurality of gas discharge holes through a gap between the dielectric material plate and the dielectric material shower plate; a flat plate slot antenna being provided on an outer side of the chamber with the dielectric material plate interposed therebetween so as to supply a microwave for exciting plasma through the dielectric material plate; an electrode being provided on an inner side of the chamber so as to hold the substrate to be processed; a lattice-like shower head provided between the dielectric material shower plate and the substrate to be processed so as to discharge a gas, which has a composition different from that of the gas discharged from the dielectric material shower plate, to a side of the substrate to be processed; and at least a part of the gas discharged from the dielectric material shower plate flows to the side of the substrate to be processed by being passed through an opening part of the lattice-like shower head, wherein said lattice-like shower head is formed of a metal pipe comprising a plurality of gas discharge holes configured and arranged such that a normal to each of said holes is oblique to the surface of the substrate, and each of said holes is formed on a curved surface of said metal pipe, and wherein said dielectric material shower plate and said lattice-like shower head are arranged substantially parallel to each other, and a distance therebetween is substantially equal to a multiple of a quarter of a wavelength of said microwave in a vacuum. 2. The plasma processing apparatus as claimed in claim 1, wherein said dielectric material plate and said dielectric material shower plate are arranged substantially parallel to each other, and a distance between a surface of said dielectric material plate facing said slot antenna and a surface of the dielectric material shower plate facing said substrate to be processed is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part.
3. The plasma processing apparatus as claimed in claim 2,
wherein said slot antenna and said dielectric material plate are arranged substantially parallel to each other, and a distance therebetween is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 4. The plasma processing apparatus as claimed in claim 1, wherein a thickness of said dielectric material shower plate is an integral multiple of a half of a wavelength of said microwave in a corresponding part.
5. The plasma processing apparatus as claimed in claim 4,
wherein said slot antenna and said dielectric material plate are arranged substantially parallel to each other, and a distance therebetween is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 6. A plasma processing apparatus for applying a process to a substrate to be processed, the plasma processing apparatus comprising:
a chamber of which interior can be depressurized; a gas supply system constructed and arranged to supply a gas to the chamber and an exhaust system configured and arranged to exhaust the gas supplied to the chamber and to depressurize the chamber; a part of a wall constituting the chamber being a flat plate dielectric material plate formed of a material which passes a microwave therethrough substantially without a loss; a flat plate dielectric material shower plate, which is formed of a material which passes a microwave therethrough substantially without a loss, being provided between the dielectric material plate and plasma excited in the chamber; a plurality of gas discharge holes being formed in the dielectric material shower plate so that at least a part of the gas supplied by the gas supply system is discharged through the plurality of gas discharge holes through a gap between the dielectric material plate and the dielectric material shower plate; a flat plate slot antenna being provided on an outer side of the chamber with the dielectric material plate interposed therebetween so as to supply a microwave for exciting plasma through the dielectric material plate; an electrode being provided on an inner side of the chamber so as to hold the substrate to be processed, wherein the slot antenna, the dielectric material plate and the dielectric material shower plate are arranged substantially parallel to each, and a distance between a surface of the dielectric material plate facing said slot antenna and a surface of said dielectric material shower plate facing said substrate to be processed is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 7. The plasma processing apparatus as claimed in claim 6,
wherein a thickness of said dielectric material shower plate is an integral multiple of a half of a wavelength of said microwave in a corresponding part. 8. The plasma processing apparatus as claimed in claim 6 or 7,
wherein a distance between said slot antenna and said dielectric material plate is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 9. A plasma processing apparatus for applying a process to a substrate to be processed, the plasma processing apparatus comprising:
a chamber of which interior can be depressurized, a gas supply system constructed and arranged to supply a gas to the chamber and an exhaust system constructed and arranged to exhaust the gas supplied to the chamber and to depressurize the chamber; a part of a wall constituting the chamber being a flat plate dielectric material plate formed of a material which passes a microwave therethrough substantially without a loss; a flat plate dielectric material shower plate, which is formed of a material which passes a microwave therethrough substantially without a loss, being provided between the dielectric material plate and plasma excited in the chamber; a plurality of gas discharge holes being formed in the dielectric material shower late so that at least a part of the gas supplied by the gas supply system is discharged through the plurality of gas discharge holes through a gap between the dielectric material plate and the dielectric material shower plate; a flat plate slot antenna being provided on an outer side of the chamber with the dielectric material plate interposed therebetween so as to supply a microwave for exciting plasma through the dielectric material plate; an electrode being provided on an inner side of the chamber so as to hold the substrate to be processed; a lattice-like shower head provided between the dielectric material shower plate and the substrate to be processed so as to discharge a gas, which has a composition different from that of the gas discharged from the dielectric material shower plate, to a side of the substrate to be processed; and at least a part of the gas discharged from the dielectric material shower plate flows to the side of the substrate to be processed by being passed through an opening part of the lattice-like shower head, wherein said dielectric material shower plate and said lattice-like shower head are arranged substantially parallel to each other, and a distance therebetween is substantially equal to a multiple of a quarter of a wavelength of said microwave in a vacuum. 10. A plasma processing apparatus for applying a process to a substrate to be processed, the plasma processing apparatus comprising:
a chamber of which interior can be depressurized, a gas supply system constructed and arranged to supply a gas to the chamber and an exhaust system constructed and arranged to exhaust the gas supplied to the chamber and to depressurize the chamber; a part of a wall constituting the chamber being a flat plate dielectric material plate formed of a material which passes a microwave therethrough substantially without a loss; a flat plate dielectric material shower plate, which is formed of a material which passes a microwave therethrough substantially without a loss, being provided between the dielectric material plate and plasma excited in the chamber; a plurality of gas discharge holes being formed in the dielectric material shower late so that at least a part of the gas supplied by the gas supply system is discharged through the plurality of gas discharge holes through a gap between the dielectric material plate and the dielectric material shower plate; a flat plate slot antenna being provided on an outer side of the chamber with the dielectric material plate interposed therebetween so as to supply a microwave for exciting plasma through the dielectric material plate; an electrode being provided on an inner side of the chamber so as to hold the substrate to be processed; a lattice-like shower head provided between the dielectric material shower plate and the substrate to be processed so as to discharge a gas, which has a composition different from that of the gas discharged from the dielectric material shower plate, to a side of the substrate to be processed; and at least a part of the gas discharged from the dielectric material shower plate flows to the side of the substrate to be processed by being passed through an opening part of the lattice-like shower head, wherein said dielectric material plate and said dielectric material shower plate are arranged substantially parallel to each other, and a distance between a surface of said dielectric material plate facing said slot antenna and a surface of the dielectric material shower plate facing said substrate to be processed is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 11. The plasma processing apparatus as claimed in claim 10,
wherein said slot antenna and said dielectric material plate are arranged substantially parallel to each other, and a distance therebetween is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part. 12. The plasma processing apparatus as claimed in claim 9,
wherein a thickness of said dielectric material shower plate is an integral multiple of a half of a wavelength of said microwave in a corresponding part. 13. The plasma processing apparatus as claimed in claim 12,
wherein said slot antenna and said dielectric material plate are arranged substantially parallel to each other, and a distance therebetween is substantially equal to an odd multiple of a quarter of a wavelength of said microwave in a corresponding part.
This application is a continuation of PCT/JP00/03365 filed on May 25, 2000.
Accordingly, a microwave plasma apparatus has recently attracting attention, which can excite high-density plasma by a microwave electric field without using a direct current magnetic field. As such kind of micro plasma apparatus, an apparatus (Japanese Laid-Open Patent Application No. 9-63793) is known, which excites plasma by ionizing a gas in a vacuum chamber by a microwave electric field generated by a microwave emitted to the vacuum chamber from a flat antenna (slot antenna) having many slots that are arranged to generate a uniform microwave. Additionally, there is also known an apparatus (WO98/33362), which excites plasma by introducing a microwave, which is emitted by a slot antenna provided outside a vacuum chamber, into the vacuum chamber by being passed through a dielectric material separation wall and a dielectric material shower plate. Since the microwave plasma excited by those methods has a high-density and a low electron temperature, a process having no damage at a high speed can be performed. Additionally, since uniform plasma can be excited even on a large area substrate, it can be easily dealt with an increase in the size of a semiconductor substrate or a liquid crystal display.
In a process for forming a thin film containing a metal such as metal thin film , feroelectric film, and high dielectric thin film by CVD (chemical vapor deposition) method, and an organometallic gas which is a compound of metal atoms and organic molecules is used. If the bonds between the metal atoms and the organic molecules is selectively cut off, a thin film having a good characteristic which causes no impurity contamination will be formed. However, if the organic molecules are decomposed, a large amount of carbon impurity atoms are mixed into the film, which deteriorates the characteristic of the thin film. Additionally, in the etching process, if the dissociation of the process gas progresses in excess, the selectivity between the film to be etched and a resist mask or the underlying material is deteriorated, and it becomes difficult to etch a fine pattern having a large aspect ratio. In the conventional microwave plasma processing apparatus, the process gas is directly introduced into an area close to a position at which the microwave is incident and having a high plasma density and a relatively high electron temperature. Thereby, the dissociation of the process gas progresses in excess, and a good result cannot be obtained in formation of a thin film using an organometallic gas or fine pattern etching.
n c=ε0ω2 m 0 /e 2 where ε0 is a permittivity of dielectric ratio of vacuum; ω is microwave angular frequency, m0 is a mass of an electron, and e is a charge of an electron. On the other hand, if the electron density is higher than the cutoff density, the microwave is reflected in the vicinity of a plasma surface. At this time, the microwave penetrates into the plasma by a penetration length (normally, several millimeters to ten millimeters), and gives energy to electrons in the plasma so that the plasma is maintained. In to the microwave plasma excitation, if the electron density is lower than the cutoff density, uniform and stable plasma cannot be excited due to dispersion of the microwave in the chamber. In order to excite uniform and stable plasma, it is indispensable to reflect a large part of the microwave by exciting plasma having an electron density sufficiently higher than the cutoff density in the vicinity of the surface on which the microwave is incident. In order to excite a stable plasma having a high electron density, an inert gas such as amyR is preferably used as the plasma excitation gas. If a gas other than a monatomic molecule gas is added, it tends to deteriorate the stability of the plasma due to the electron density being decreased since the energy of the microwave is used for dissociation of the gas molecules. In the conventional microwave plasma apparatus, since only a small amount (several percent) of gas other than the inert gas can be added, there is a problem in that process window is narrow and it cannot deal with a high speed process.
When the electron density in the vicinity of the plasma surface is higher than the cutoff density, a large part of the microwave incident on the plasma is reflected in the vicinity of the surface. The reflected wave is received by the slot antenna, and, thereafter, emitted form the slot antenna by being reflected by a matching unit connected between the slot antenna and the microwave power source. The microwave gradually provides its energy to the plasma while repeatedly reflected between the plasma surface and the matching unit. That is, the microwave is in a resonant state in a part between the plasma surface and the matching unit. Accordingly, a high energy density microwave is present in this part, and a large loss is caused due to a small conductive loss of a metal wall of the waveguide or a small dielectric loss of the dielectric material. In the conventional microwave plasma apparatus, these losses are large, and, thereby, the plasma excitation power efficiency was low. Additionally, if a large power microwave is supplied so as to obtain a high-density plasma, an arc discharge is generated in a slot part formed on the surface of the slot antenna. Thereby, there is a problem in that the antenna is broken or a discharge occurs in a gas passage between the dielectric material separation wall and the dielectric material shower plate.
An area of the grounded part to which the plasma contacts is greatly increased by introducing the grounded metal made lattice-like shower plate into the plasma. When a RF bias is applied to the substrate, a large part of the RF voltage can be applied to a sheath near the substrate, and, thereby, the energy of ions incident on the surface of the substrate can be efficiently increased without increasing a potential of the plasma. Accordingly, the present invention can be effectively applied to a process such as a reactive ion etching in which a high ion-energy must be incident on a surface of a substrate.
FIG. 12 is a cross-sectional view taken along a line XII�XII of FIG. 11.
A description will now be given, with reference to the drawings, of plasma processing apparatuses according to embodiments of the present invention, but, the present invention is not limited to the embodiments.
In the present embodiment, the vacuum chamber 101 is formed of aluminum, and the dielectric material separation wall 102 and the dielectric material shower plate 103 are formed of aluminum nitride having a relative permittivity of 8.63. A frequency of a microwave for plasma excitation is 2.45 GHz. The substrate. 114 is a silicon substrate having a diameter of 200 mm.
A microwave emitted by the radial line slot antenna 110 located in an atmosphere is introduced into an interior of the vacuum chamber 101 by being passed through the dielectric material separation wall 102, eth gap 104 and the dielectric material shower plate 103, and generates plasma by ionizing a gas in the vacuum chamber 101.
FIG. 2 is a plan view of the lattice-like shower plate 111 viewed from the side of the substrate 114. The lattice-like shower plate 111 comprises a main pipe 201, branch pipes 202, the process gas discharge holes 113 and lattice-like shower plate gas supply ports 204. A circle indicated by a dashed line is an area facing the substrate 114. In the present embodiment, two lattice-like shower plate gas supply ports 204 are provided so as to evenly discharge the gas onto the substrate 114. The main pipe 201 and the branch pipes 202 are metal pipes having other diameter of 9.53 mm (⅜ inches) and 6.35 mm (� inches), respectively, and connection parts therebetween are welded. The branch pipes 202 are positioned in a lattice arrangement, and openings 206 are formed between the main pipe 201 and the branch pipes 202. The branch pipes 202 are provided with many gas discharge holes 113 at positions at which the process gas is obliquely incident on the surface of the substrate evenly over the entire surface of the substrate. In the present embodiment, although the process gas is obliquely incident on the surface of the substrate so as to improve substrate in-plane uniformity of a process, the process gas may be vertically incident on the surface of the substrate.
In the present embodiment, a high-density aluminum containing stainless steel, which contains a larger amount of an aluminum component (4.16%) than that of the conventionally used stainless steel SUS316L, is used for the material of the pipes, and the pipes are treated at a high temperature (900� C.) in a low oxidization atmosphere so as to form an aluminum oxide passivation film which is extremely thermodynamically stable, on the surfaces of the pipes so that the pipes can be semi-permanently used eave in a corrosive gas plasma atmosphere. It has been found that the formation of the aluminum oxide passivation film provides an excellent corrosion resistance with respect to plasma of a corrosive gas such as chlorine gas or fluorine gas
The radial line slot antenna 110, the dielectric material separation wall 102, the dielectric material shower plate 103, the lattice-like shower plate 11 and the substrate 114 are positioned parallel to each other. A distance between the dielectric material shower plate 103 and the lattice-like shower plated 11 is set to a quarter (30 mm) of a wavelength of the microwave in a vacuum; a distance between the surface of the dielectric material separation wall facing the antenna 110 and the surface of the dielectric material shower plate 103 facing the substrate 114 is set to three quarters (30.7 mm including the gap 104 of 0.7 mm) of a wavelength of the microwave in the corresponding part; a thickness of the dielectric material shower plate is set to a half (20 mm) of a wavelength of the microwave in the corresponding part. Further, a distance between the radial line slot antenna and the dielectric material separation wall is set to a quarter (30 mm) of a wavelength of the microwave.
If the lattice-like shower plate 11 shown in FIG. 2 is situated in the chamber, a contamination may occur since the material of the shower plate is sputtered by bombardment of ions from the plasma onto a surface of the shower plate and the sputtered material enters near the surface of the substrate. A sheath is formed near a surface of an object inserted into plasma, and ions in the plasma are accelerated by the electric field in the sheath and incident on the surface of the object. If the energy of the incident ions is equal to or greater than a threshold value peculiar to the material or the ions, a sputtering occurs, but if less than the threshold value, no sputtering occurs. For example, when Ar+ ions are incident on a surface of various metals, the threshold value is about 10 eV to 30 eV. In order to prevent a contamination due to sputtering, the energy of ions incident on the lattice-like shower plate 111 is preferably reduced to about 10 eV.
The measurement of the electron density was performed at a position away from a wafer by 15 mm along a center axis of the wafer. As for the process gas, a gas produced by bubbling Ar carrier gas in liquefied Ta(O�C2H5)5 was used. As for the plasma excitation gas, Ar was used. Flow rate of the process gas and the plasma excitation gas ware 150 sccm and 500 sccm, respectively, and the pressure in the vacuum chamber was about 80 Pa (0.6 Torr). A frequency of the microwave for plasma excitation was 2.45 GHz, and a power thereof was 1.1 kW.
In the conventional structure, the electron density was gradually decreased after a deposition time of 3 minutes has passed and the plasma became unstable, and finally the plasma disappeared when 11 minutes has passed. This is because the tantalum film deposited on the surface of the dielectric material shower plate 103 reflected and absorbed the microwave. As a result of accrual analysis of the film deposited on the surface of the dielectric material shower plate 103, it was found that a tantalum film containing a large amount of carbon was deposited. An average thickness of the tantalum film was 4.3 μm.
Further, when an electric resistivity of the tantalum thin film, the resistivity was 225�10−6 Ωcm due to a large amount of carbon contained therein in the conventional structure, while the resistivity was 21�10−6 Ωcm which was lower more a single digit lower than that of the conventional structure, and it was found that an almost ideal thin film was formed. As mentioned above, the characteristic of the thin film can be greatly improved by applying the plasma processing apparatus according to the present invention to a CVD process of a metal thin film, a feroelectric thin film or a high permittivity thin film.
Comparison of etching characteristics when
etching is performed by a conventional apparatus and the
Etchig selectivity of a
In order to realize a next generation ultra fine high-performance semiconductor device, the selectivity between a resist and a silicon oxide film must be equal to or greater than 10, and the selectivity between a silicon nitride film and a silicon oxide film must be equal to or greater than 30. In the conventional structure, a sufficient etching selectivity cannot be obtained with respect to both the resist and the silicon nitride film since decomposition of fluorocarbon gas progresses in excess which generates a large amount fluorine radicals or fluorine ions causing a decrease in the selectivity. Additionally, since the surface of the grounded part such as a chamber wall is subjected to sputtering and sputtered material enter a silicon surface on the bottom of the contact hole, a contact resistance becomes very high. Since it cannot be used for a device as it is, there is needed a process of removing a damaged layer in the vicinity of the surface of the silicon, which causes an increase in a semiconductor manufacturing cost and a decrease in the productivity.
The electron density (higher than 1012cm−3) near the surface on which the microwave is incident is sufficiently higher than a cutoff density (45�1010 cm−3), the microwave incident on the plasma surface cannot enter the plasma deeper than an entering length (about 3 mm) from the surface of the plasma. The reflected microwave is received by the antenna, and, thereafter, reflected by the matching unit and emitted from the antenna. That is, a space between the plasma surface and the matching unit is in a resonant state. In this space, a microwave having a high-energy density is present, and, thereby, a large loss is generated due to a small conductor loss or a small dielectric loss of the dielectric material in the slot antenna. If the loss is larger than a power supplied from the microwave to the plasma, the power density of the microwave between the plasma surface and the matching unit rarely depends on a state of the plasma. On the assumption that the power density of the microwave in the resonator is constant, the power density of the microwave in the dielectric material part is maximized when the thickness of the dielectric material part is such that the surface thereof facing the antenna is at a position corresponding to a loop of the standing wave of the microwave electric field, and the plasma can be most effectively excited. On the contrary, the power density of the microwave in the dielectric material part is minimized when the thickness of the dielectric material part is such that the surface thereof facing the antenna is at a position corresponding to a node of the standing wave of the microwave electric field, and the efficiency of plasma excitation becomes lowest. In order to locate the surface of the dielectric material part facing the antenna at a position of the loop of the standing wave of the microwave electric field, a distance between the surface of the dielectric material separation wall facing the antenna and the surface of the dielectric material shower plate facing the substrate is set equal to an odd multiple of a quarter of the wavelength in the corresponding part. This is because the surface of the dielectric material shower plate 103 facing the substrate can be regarded as a short-circuit plane (position of a node of the standing wave) due to the presence of the plasma which can be regarded as a conductor. It can be appreciated from FIG. 7 that the thickness of the dielectric material part at which the electron density takes a maximum value is 30 mm and 50 mm. These values correspond to the distance between the surface of the dielectric material separation wall facing the antenna and the surface of the dielectric material shower plate facing the substrate being three quarters and five quarters of the wavelength, respectively.
In the conventional structure, since the thickness of the dielectric material part is determined based on only a mechanical strength thereof, there are many cases in which the efficiency of plasma excitation is low, and the efficiency varies for each apparatus. In the structure of the present invention, the efficiency of plasma excitation is as high as 75% and reaches 3.6 times that of the conventional structure at a maximum. That is, high-density plasma can be generated by a small, inexpensive microwave power source with less power consumption.
When the distance between the dielectric material shower plate 103 and the substrate 114 becomes larger than a quarter of the wavelength, a discharge abruptly becomes to be difficult to occur in the process space. This can be explained as follows. The lattice-like shower plate 111 constituted by a metal serves a short-circuit plane for the microwave if the lattice interval is sufficiently shorter than the wavelength of the microwave. After the microwave is supplied to the chamber, the wave incident on the lattice-like shower plate 111 and the reflected wave reflected near the surface of the lattice-like shower plate 111 together form a standing wave. If the distance between the dielectric material shower plate 103 and the lattice-like shower plate 111 is longer than a quarter of the wavelength, a loop of the standing wave of the microwave electric field is present in the plasma space, and a discharge begins at a position where the electric field is strong. Immediately after the discharge begins, high-density plasma is generated near the surface on which the microwave is incident by using the plasma as a seed. On the other hand, if the distance between the dielectric material shower plate 103 and the lattice-like shower plate 111 is shorter than a quarter of the wavelength, the microwave electric field is maximized in the surface of the dielectric material shower plate 103, but the intensity of the electric field decreases as the distance decreases, which results in less discharge.
FIG. 10 is a graph showing a result of measurement of a power density of the microwave at which a discharge begins in the slot part of the antenna 110 when the distance between the radial line slot antenna 110 and the dielectric material shower plate 103 is varied while the thickness of the dielectric material part is fixed to 30 mm. It can be appreciated that the power density of the microwave at which a discharge begins in the slot part periodically varies with the distance between the radial line slot antenna 110 and the dielectric material shower plate 103. If a discharge occurs in the slot part, the antenna 110 is damaged, and the plasma in the process space becomes unstable, and, thus, such a discharge must be positively prevented. In order to prevent the discharge in the slot part, the distance between the antenna 111 and the dielectric material shower plate 103 is determined so that the surface of the antenna 110 is located at a position of a node of the standing wave of the microwave electric field. When the surface of the dielectric material shower plate 103 facing the antenna corresponds to a loop of the standing wave of the microwave electric field, that is, in a case in which eth surface of the dielectric material separation wall facing the antenna and the surface of the dielectric material shower plate 103 facing substrate is set equal to an odd multiple of a quarter of the wavelength in the corresponding part, the distance between the antenna 110 and the dielectric material shower plate 103 can be an odd multiple of a quarter of the wavelength. It can be appreciated from FIG. 10 that a discharge most hardly occurs when the distance between the antenna 110 and the dielectric material shower plate 103 is 30 mm and 90 mm, and most easily occurs when the distance is 60 mm. These values correspond to a quarter, two quarters and three quarters of the wavelength, respectively.
A description will now be given, with reference to FIG. 11 and FIG. 12, of a plasma processing apparatus according to a second embodiment of the present invention. FIG. 11 is a plan view of a lattice-like shower plate 600 provided in the plasma processing apparatus according to the second embodiment of the present invention viewed from a side of a substrate. FIG. 12 is a cross-sectional view taken along a line XII�XII of FIG. 11. The plasma processing apparatus according to the second embodiment of the present invention is the same as the plasma processing apparatus according to the first embodiment of the present invention shown in FIG. 1 except for the lattice-like shower plate 600 shown in FIG. 11, and descriptions thereof will be omitted.
A description will now be given, with reference to FIG. 13 and FIG. 14, of a plasma processing apparatus according to a third embodiment of the present invention. FIG. 13 is a plan view of a lattice-like shower plate 700 provided in the plasma processing apparatus according to the third embodiment of the present invention viewed from a side of a substrate. FIG. 14 is a cross-sectional view taken along a line XIV�XIV of FIG. 13. The plasma processing apparatus according to the third embodiment of the present invention is the same as the plasma processing apparatus according to the first embodiment of the present invention shown in FIG. 1 except for the lattice-like shower plate 700 shown in FIG. 13, and descriptions thereof will be omitted.
FIG. 15 is a cross-sectional view of a plasma processing apparatus according to a fourth embodiment of the present invention. The plasma processing apparatus according o the fourth embodiment of the present invention comprises a vacuum chamber 801, a dielectric material separation wall 802, dielectric material shower plates 803, a gap 804, a shower plate fixing jig 805, plasma excitation gas supply ports 806, plasma excitation gas discharge holes 807, microwave guides 808, a lattice-like shower plate 809, process gas supply ports 810, process gas discharge holes 811, a stage.813 and an exhaust port 814. A substrate 812 to be processed by plasma is placed on the stage 813.
In the present embodiment, the vacuum chamber is formed of aluminum; the dielectric material separation wall 802 is formed of aluminum oxide; the dielectric material shower plates 803 are formed of aluminum nitride; and the shower plate fixing jig 805 is formed of aluminum. The lattice-like shower plate 809 has the same structure as that of one of the above-mentioned first to third embodiments, and is formed of a high-concentration aluminum containing stainless steel which is subject to an oxidation passivation treatment, similar to the above-mentioned first embodiment. The frequency of the microwave for plasma excitation is 2.45 GHz. The substrate 812 is a square glass substrate for a liquid crystal display, and its size is 550�650 mm2.
Each process for manufacturing a liquid crystal display
and process conditions thereof
SiH4 (50 sccm)
NH3 (70 sccm)
SiH4 (60 sccm)
Approx. 60 Pa
silicon film forming
3: n+ silicon
PH3 (20 sccm)
SF6 (250 sccm)
O2 (90 sccm)
The following Table 3 indicates a comparison of results of execution of the same process by a parallel flat plate type plasma processing apparatus (conventional apparatus), which is widely used in the recent manufacturing of liquid crystal displays and the plasma processing apparatus according to the present embodiment.
voltage : 4.2 MV/cm
voltage : 12.4 MV/cm
rate : 120 nm/min
rate : 310 nm/min
(0.2 cm2/V � sec)
rate : 78 nm/min
rate : 93 nm/min
3: n+silicon
2.3 �cm
0.7 �cm
rate : 58 nm/min
rate : 85 nm/min
Etching rate :
thickness : 7 nm
thickness : 28 nm
(oxidation time,
The silicon nitride film is used as a gate insulating film or an interlayer insulating film, and is required to be deposited at a high rate in the form of a film having a high withstand voltage and a small leak current. In the apparatus according to the present embodiment, since the energy of ions incident on the surface on which the film is deposited is as low as one-third of that of the conventional apparatus and there is no damage to the thin film due to ion bombardment, a high-quality silicon nitride film is formed, which has a withstand voltage close to three times that of the conventional one. Further, since the electron density is higher than the conventional parallel flat plate type plasma apparatus by about one order (>2�1012 cm−3), a film deposition rate is high and productivity is remarkably increased.
The silicon film is used for a channel part, which is an important part of the TFT. A silicon film having a high channel moving speed must be deposited on an insulating film so as to improve a current drive performance of a transistor. In the conventional apparatus, the moving speed was very low (0.2 cm2/V�sec) since it was able to form only an amorphous film. Although a polycrystalline silicon film having a high moving speed can be obtained by performing a laser annealing treatment which polycrystallizes an amorphous film by irradiating a laser beam, this method is not practical since it takes a very long time. When the microwave plasma processing apparatus according to the present invention is used, a polycrystalline silicon film having a high moving speed of about 280 cm2/V�sec was able to be deposited by a CAD method at a low substrate temperature of 250� C. without annealing. Additionally, the microwave plasma processing apparatus according to the present invention is capable of depositing a film at a high rate and has an excellent productivity, and provides an innovative thin film forming technology.
In order to achieve an insulation between the source and the drain, the No silicon film (thickness of the film is about 15 mm) must be completely oxidized up to the inside thereof. At this time, the temperature of the substrate must be lower than 300� C. If a low-temperature plasma oxidation is performed by the conventional apparatus, the oxidation progresses up to a depth of only about 7 mm. Accordingly, the film cannot be oxidized in its entirety, and an insulation between the source and the drain cannot be achieved. On the other hand, according to the apparatus of the present embodiment, the source and the drain can be completely insulated from each other by oxidizing the n+ silicon film in its entirety since the oxidation progresses up to a depth of 28 mm at a substrate temperature of 300� C. for 3 minutes. This is because a large amount of oxygen radicals, which are seeds of oxidation, are generated due to a high electron density, and diffusion of the oxygen radicals into the oxidation film is promoted by a large amount of ions irradiated onto the surface of the substrate.
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H01J37/32O2, C23C16/34C, C23C16/511, C23C16/455K14, C23C16/24, C23C16/455K2Legal EventsDateCodeEventDescriptionMay 16, 2012FPAYFee paymentYear of fee payment: 8May 30, 2008FPAYFee paymentYear of fee payment: 4Jun 7, 2005CCCertificate of correctionMay 24, 2005CCCertificate of correctionOct 4, 2000ASAssignmentOwner name: TADAHIRO OHMI, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OHMI, TADAHIRO;HIRAYAMA, MASAKI;REEL/FRAME:011221/0347Effective date: 20000912Owner name: TOKYO ELECTRON LIMITED, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OHMI, TADAHIRO;HIRAYAMA, MASAKI;REEL/FRAME:011221/0347Effective date: 20000912Owner name: TADAHIRO OHMI AOBA-KU, SENDAI-SHI 1-17-301, KOMEGAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OHMI, TADAHIRO /AR;REEL/FRAME:011221/0347RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent 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