Patent CA770499A successfully refreshed from Google Patents.
Patent US5203960A successfully refreshed from Google Patents.
US5203960A
Expired / Lapsed
US
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Method of operation of electron cyclotron resonance plasma source
Assignee: Applied Microwave Plasma Concepts Inc
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Filing: 1992-04-29
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Granted: 1993-04-20
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Expires: 2012-04-29
Abstract
Abstract A method is disclosed employing electron cyclotron resonant (ECR) heating to produce plasma for applications including but not limited to chemical vapor deposition and etching. A magnetic field is formed by magnets circumferentially arranged about a cylindrical and symmetrical chamber with microwave power injected perpendicularly to a longitudinal axis of the chamber for preventing line-of-sight communication of resulting energetic electrons through an outlet at one axial end of the chamber. The circumferential magnets in the symmetrical chamber cause precessing of the electrons resulting in greatly increased plasma density and ion flux or current density even at low gas pressures which are preferably maintained for establishing unidirectionality or anisotropic plasma characteristics. A magnetic field free region is formed between the plasma forming region containing the microwave power source and the circumferential magnets in order to also produce uniformity of plasma distribution in a plasma stream approaching the outlet. Thus, with specimens arranged in communication with the outlet, the above characteristics are maintained for the plasma stream over substantial transverse dimensions larger than the specimen.
Inventors
- 👤 Raphael A. Dandl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:45
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32192; H01J37/32211; H01J37/32229; H01J37/32431; H01J37/3266; H01J37/32678; H05; H05H; H05H1/00; H05H1/02; H05H1/16; H05H1/18; H01J2237/00; H01J2237/32; H01J2237/33; H01J2237/332; H01J2237/3322; H01J2237/3323; H01J2237/334; H01J2237/3343; H01J2237/3345
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
263 words
A method of generating plasma by electron cyclotron resonant (ECR) heating to treat specimens by processes including chemical vapor deposition and etching, comprising the steps of forming a cylindrical chamber which is symmetrical about its longitudinal axis, supporting one of the specimens adjacent one axial end of the cylindrical chamber, introducing a gaseous medium into the chamber, generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof, developing a substantially field free region adjacent the one axial end of the chamber while minimizing the extension of magnetic field force lines into the magnetic field free region and toward the specimen, uniformly radiating electromagnetic radiation from a microwave power injector arranged between the magnet assemblies and having multiple injection axes extending radially inwardly toward the longitudinal axis of the chamber toward the resonant interaction region about the entire periphery of the chamber so that plasma electrons made energetic by interaction with the electromagnetic radiation are not permitted line of sight communication to the specimen along magnetic field force lines in the magnetic field free region, and maintaining low gas pressure in the chamber whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions larger than the specimen, low plasma temperature and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10 -5 Torr.
Claim 2
Independent Claim
263 words
A method of generating plasma by electron cyclotron resonant (ECR) heating to treat specimens by processes including chemical vapor deposition and etching, comprising the steps of forming a cylindrical chamber which is symmetrical about its longitudinal axis, supporting one of the specimens adjacent one axial end of the cylindrical chamber, introducing a gaseous medium into the chamber, generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof, developing a substantially field free region adjacent the one axial end of the chamber while minimizing the extension of magnetic field force lines into the magnetic field free region and toward the specimen, uniformly radiating electromagnetic radiation from a microwave power injector arranged between the magnet assemblies and having multiple injection axes extending radially inwardly toward the longitudinal axis of the chamber toward the resonant interaction region about the entire periphery of the chamber so that plasma electrons made energetic by interaction with the electromagnetic radiation are not permitted line of sight communication to the specimen along magnetic field force lines in the magnetic field free region, and maintaining low gas pressure in the chamber whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions larger than the specimen, low plasma temperature and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10 -5 Torr.
Claim 3
Dependent Claim
72 words
The method of claim 1 wherein the microwave power injector is further arranged relative to the magnetic field so that resulting energetic electrons are caused either to experience multiple collisions with the magnetic field force lines or to precess in annular magnetic mirror regions formed by the magnet assemblies whereby the likelihood of collision of the energetic electrons with gas atoms is enhanced resulting in increased plasma density at low gas pressure.
Claim 4
Dependent Claim
56 words
The method of claim 2 wherein the microwave power injector comprises a slotted wave guide formed circumferentially about the chamber and having its multiple injection axes arranged parallel to lines of magnetic force developed by the magnet assemblies for producing more symmetric and uniform coupling of microwave power in the chamber and for achieving over-dense operation.
Claim 5
Dependent Claim
55 words
The method of claim 1 wherein the other end of the chamber is closed and provided with circumferentially extending and circumferentially symmetrical magnet means for developing continuous magnet field force lines, the microwave power injector and circumferentially continuous magnet assemblies being arranged in a plasma forming portion of the chamber adjacent its other closed end.
Claim 6
Dependent Claim
47 words
The method of claim 4 further comprising the step of forming insulating magnetic means circumferentially continuous about the magnetic field free region to prevent interaction of the plasma with walls of the chamber while avoiding development of magnetic field force lines in the magnetic field free region.
Claim 7
Dependent Claim
28 words
The method of claim 3 wherein the microwave power injector comprises a slotted wave guide arranged in an annular recess formed between the two circumferentially arranged magnet assemblies.
Claim 8
Dependent Claim
43 words
The method of claim 6 further comprising the step of forming impurity trapping recesses annularly adjacent the magnet assemblies for receiving energetic electrons and accompaying ions leaking from the annular magnetic mirror regions and preventing the resulting gas from returning to the chamber.
Claim 9
Dependent Claim
55 words
The method of claim 1 wherein the microwave power injector comprises a slotted wave guide arranged circumferentially about the chamber and having multiple injection axes arranged parallel to lines of magnetic force developed by the magnet assemblies for producing more symmetric and uniform coupling of microwave power in the chamber and for achieving over-dense operation.
Claim 10
Dependent Claim
73 words
The method of claim 8 further comprising the step of forming impurity trapping recesses annularly adjacent the magnet assemblies for receiving energetic electrons and accompaying ions leaking from the annular magnetic mirror regions and preventing the resulting gas from returning to the chamber, the magnet assemblies comprising means tending to close the magnetic field force lines tightly thereabout in order to minimize random field force lines extending into the magnetic field free region.
Claim 11
Dependent Claim
36 words
The method of claim 1 wherein the magnet assemblies comprise means tending to close the magnetic field force lines tightly thereabout in order to minimize magnetic field force lines extending into the magnetic field free region.
Claim 12
Independent Claim
245 words
A method for producing a high density plasma by an electron cyclotron resonance (ECR) comprising forming a cylindrical chamber which is symmetrical about its longitudinal axis and has an outlet at one axial end thereof, introducing a gaseous medium into the chamber, generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof, developing a substantially field free region adjacent the one axial end of the chamber while minimizing the extension of magnetic field force lines into the magnetic field free region, uniformly radiating electromagnetic radiation from a microwave power injector arranged between the magnet assemblies and having multiple injection axes extending radially inwardly toward the longitudinal axis of the chamber toward the resonant interaction region about the entire periphery of the chamber so that plasma electrons made energetic by interaction with the electromagnetic radiation are not permitted line of sight communication toward the outlet along field force lines in the magnetic field free region, and maintaining low gas pressure in the chamber whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions almost as large as the outlet, low temperature plasma and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10 -5 Torr.
Claim 13
Independent Claim
245 words
A method for producing a high density plasma by an electron cyclotron resonance (ECR) comprising forming a cylindrical chamber which is symmetrical about its longitudinal axis and has an outlet at one axial end thereof, introducing a gaseous medium into the chamber, generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof, developing a substantially field free region adjacent the one axial end of the chamber while minimizing the extension of magnetic field force lines into the magnetic field free region, uniformly radiating electromagnetic radiation from a microwave power injector arranged between the magnet assemblies and having multiple injection axes extending radially inwardly toward the longitudinal axis of the chamber toward the resonant interaction region about the entire periphery of the chamber so that plasma electrons made energetic by interaction with the electromagnetic radiation are not permitted line of sight communication toward the outlet along field force lines in the magnetic field free region, and maintaining low gas pressure in the chamber whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions almost as large as the outlet, low temperature plasma and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10 -5 Torr.
Claim 14
Dependent Claim
55 words
The method of claim 11 wherein the microwave power injector comprises a slotted wave guide formed circumferentially about the chamber and having multiple injection axes arranged parallel to lines of magnetic force developed by the magnet assemblies for producing more symmetric and uniform coupling of microwave power in the chamber and for achieving over-dense operation.
Claim 15
Dependent Claim
25 words
The method of claim 12 wherein the other end of the chamber is closed and provided with magnet means for developing magnetic field force lines.
Claim 16
Dependent Claim
46 words
The method of claim 11 wherein the microwave power injector and circumferentially continuous magnet assemblies are arranged in a plasma forming portion of the chamber adjacent its other closed end and a magnetic field free region is formed adjacent the one axial end of the chamber.
Claim 17
Dependent Claim
46 words
The method of claim 14 comprising the step of forming insulating magnet means circumferentially extending about the magnetic field free region to prevent interaction of the plasma with walls of the chamber while avoiding development of magentic field force lines in the magnetic field free region.
Claim 18
Dependent Claim
26 words
The method of claim 15 wherein the microwave power injector comprises a slotted wave guide arranged in an annular recess formed between the two magnet assemblies.
Claim 19
Dependent Claim
41 words
The method of claim 16 further comprising impurity trapping recesses annularly formed adjacent the magnet assemblies for receiving energetic electrons and accompaying ions leaking from the annular magnetic member regions and means for preventing resulting gas from returning to the chamber.
References Cited (Backward Citations)
US4745337A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-19 | 1996-10-19 | 1997-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-19 | 2000-10-19 | 2001-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-19 | 2004-10-19 | 2005-04-20 | $7700.00 | Window Closed / Lapsed |