A
`
`V
`FRANI< B . DEHN 8 C O .
`M k
`ar Attorneys
`
`Patent and Trade
`
`
`
`Page 1 of 21
`St Bride's House, 10 Salisbury Square, London EC4Y 8JD
`Telephone: +44 (0)20 7632 7200 Fax: +44 (0)20 7353 8895
`Email: mail@frankbdehn.com Web: www.frankbdehn.com
`
`date 24 July 2007
`your ref
`our ref 31.32.89113
`
`EPO - Munich
`63
`25. lull 2007
`
`European Patent Office
`D—80298 Miinchen
`Germany
`
`Dear Sirs
`
`European Patent Application No. 047169283 (1614136)
`Regional Phase of PCT Application PCT/USZOO4/006456
`Zond, Inc.
`
`In reply to the Official Communication dated 15 December 2006, we enclose replacement pages
`1, 2, 23, 3, 4, 9, 23, 26-28, 30—32 and 34—37 to replace the pages 1—4, 9, 23, 26-28, 30-32 and
`34—37 currently on file.
`
`The Examiner objected that the independent claims 1 and 15 lacked novelty over documents D1
`and D2. Amended apparatus claim 1 now includes the feature of claim 2, namely that the
`excited atom source comprises a magnet for trapping electrons proximate to the ground state
`atoms. Method claim 15 (now claim 14) has been similarly amended.
`
`In the examination report, with regard to claim 2, the Examiner referred back to the IPRP. In
`that report, the Examiner gave the opinion that claim 2 also lacked novelty over D1 and D2, but
`gave no detailed reasoning. We respectfully disagree with his objection.
`
`D1 discloses a first plasma generating means which excites atoms to a metastable state and a
`second plasma generating means for activating the gas. However, D1 does not disclose the use
`of a magnet anywhere within the apparatus. In particular, D1 does not disclose the use of a
`magnet within the firstplasma generating means for trapping electrons proximate to the ground
`state atoms as require by amended claim 1.
`
`D2 relates to a continuous plasma laser. In D2, the multiple anodes and cathodes along the
`length of the chamber excite the atoms into a metastable state to await stimulated emission back
`to the ground state. The whole apparatus of D2 therefore may be considered an excited atom
`source. However, D2 does not disclose a further anode and cathode separate from the excited
`atom source which are used together with a power supply to ionize the excited atoms.
`
`Annabel R Beacham MA own 0 Associates
`John P Tothill MA 0
`Derek P Manhawsas: PhD '
`Partners
`Adrian SamuelsMA '
`Jason Stevens BA '
`Hanna Dzi
`lewsita BSc PhD 0' John C Marsden MA t
`Christopher P Port MA 0'
`Roberto Ca amitaMA "
`Robert P Jackson as: LLM ‘ Neil Campbell BA '
`Joseph M Letang LLB '
`Kerry J Tomlinson MA '
`David Leakey 35c ‘ '
`Elizabeth Jones MSc PhD 0 Charlotte Stirling MA '
`Deborah J Owen MA PhD .
`Michael J ButlerMA 0'
`Julian Coekbain MA DPhli r' Alison J Hague MA °'
`Louise A GoldingMA ‘
`Philip M Webber MA rho '
`Katherine F Mabey MA '
`Christopher R Davies 65: " Philip D Towler MA -'
`Rebeeca Gardner 85c '
`Matthew Hall BA MS: ~
`Christopher R Goddard MA PhD '
`Alexander J Piésold as: t ' Andrea M Hughesaavg rm 0' Philip M Jeffrey 851: PhD 0
`Elaine P Deyes 35¢ -
`Catherine L Booth :5: PhD '
`‘UK Chartered Patent Attorney. European Patent Attorney 'UK Registered Trade Marl: Attorney, European Trade Mark Attorney
`
`Kirsteen H Gordon 35c PhD t
`Susannah Neath 85¢ ‘
`Clare L Stoneman BA ‘
`Anna Leathley MW PhD ‘
`Andrew Chive Msd ‘
`
`Offices in London Munich Brighton Oxford
`
`lNTE L 1 01 0
`
`Page 1 of 21
`
`INTEL 1010
`
`

`

`24 July 2007
`31.32.89113
`
`_ 2 -
`
`.
`
`Page 2 of21’
`FRANK B. DEHN Er Co.
`
`We therefore submit that independent claims 1 and 14 (previously 15) are novel over both
`documents D1 and D2.
`
`The closest prior art for the purpose of assessing inventive step is D1 as it is in the same
`technical field as the present invention and addresses the same problem of improving plasma
`activation efficiency.
`
`The difierence between claim 1 and the apparatus of D1 is the provision of a magnet in the
`excited atom source for trapping electrons proximate to the ground state atoms. Starting from
`D1, the technical problem facing a skilled person is the further improvement in activation
`efficiency and the solution provided by claim 1 is the generation of a magnetic field for trapping
`electrons in the excited atom source. D1 provides no hint or suggestion that magnets should be
`used anywhere in the apparatus, let alone specifically in the lst plasma generation means. We
`therefore submit that claim 1 is inventive over D1.
`
`As mentioned above, D2 relates to a different technical field, i.e. the field of lasers. Although
`the apparatus of D2 may (as mentioned above) be considered to be an excited atom source, we
`submit that a skilled person faced with the above problem would not consider looking to the
`field of lasers when trying to solve it. In lasers, atoms are raised to the metastable state so that
`they can be stimulated back to the ground state. In contrast, in the two—step plasma generation
`process of the present invention, atoms are raised to the metastable state as a preliminary stage
`before ionization. The apparatuses are therefore fundamentally difierent.
`
`Further even if the skilled person were to look to the teachings of D2, we submit that he would
`still not arrive at the teachings of the present invention. Although D2 teaches the application of
`a magnetic field within the chamber (via solenoid 151, column 11, lines 36-36), the field is not
`for the purpose of trapping electrons. Rather the field is used to forcibly move atoms away from
`their origin by driving them to another anode further down the chamber (column 11, lines 53—
`58). D2 therefore teaches away from the present invention.
`
`We therefore submit that claim 1 is also inventive over a combination of documents D1 and D2.
`
`The above arguments have been given in respect of apparatus claim 1, but they apply equally to
`method claim 14.
`
`As requested by the examiner, we have also acknowledged both documents D1 and D2 in the
`description and we have inserted a statement of invention corresponding to amended claim 1.
`Reference numbers have been added to the claims and the independent claims have been
`characterised over document D1. SI units have been inserted into the description next to their
`non—SI counterparts. We have also corrected the errors noted by the Examiner in paragraphs
`[0119] and [0142] and we have removed the phrase "Spirit and" from the last paragraph of the
`description.
`
`Page 2 of 21
`
`

`

`Page 3 of 21
`FRANK B. DEHN Er Co.
`
`24 July 2007
`31.32.89113
`
`_ 3 -
`
`We trust that this application is now in order for grant. However, in the event that the
`examining division intend to reject the application at any stage, we hereby request Oral
`Proceedings.
`
`Form 1037 is enclosed for acknowledgement purposes.
`
`Yours faithfully
`Frank B. Dehn & Co.
`
`Robert Jackson
`
`Encs
`
`Page 3 of 21
`
`

`

`Page 4 of 21
`St Bride's House, 10 Salisbury Square. London EC4Y 8JD
`Telephone: +44 (0)20 7632 7200 Fax: +44 (0)20 7353 8895
`E-mail: mail©frankbdehn.com Web: www.frankbdehn.com
`
` ~
`
`g
`FRANK B .‘ DEHN 8 C O .
`
`t dTrdeMrkAtto
`Pt
`a an an
`a
`a
`
`rney
`
`s
`
`European Patent Ofiice
`D-80298 Miinchen
`Germany
`
`date 24 July 2007
`your ref
`our ref 31.32.89113
`
`EPO - Munich
`63
`
`25. Juli 2007
`
`Dear Sirs
`
`European Patent Application No. 047169283 (1614136)
`Regional Phase of PCT Application PCT/USZOO4/006456
`Zond, Inc.
`
`I hereby request further processing of this application in accordance with Article 121 EPC.
`
`I enclose a Fee Voucher authorising the withdrawal of the further processing fee fiom our
`Deposit Account No. 28050069 in respect of the fee for further processing.
`
`A response to the Official Communication of 15 December 2006 is filed herewith.
`
`A Form 1037 is enclosed for acknowledgement purposes.
`
`& Co.
`
`Zu‘. Kasse
`
`.
`
`Yours faithfully
`
`Frank B. De
`
`
`
` Robert Jackson
`
`Encs
`shr
`
`Annabel R Beachamm onin ' Associates
`John P Tothill MA ‘
`Derek P Matthews BS: PhD ’
`Partners
`Adrian Samuels MA '
`Jason Stevens BA '
`Christopher P PettMA " Hanna Dzie lewska BSc PhD " John C Marsden MA 0
`Kerry J Tomlinson MA '
`Roberto Ca amita MA "
`Robert P Jackson 35c LLM ' Neil Campbell BA 0
`Joseph M Letang LLB '
`Michael J Butler MA "
`David Lackey as: "
`Elizabeth Jones MS: PhD ' Charlotte Stirling MA ’
`Deborah J Owen MA PhD 0
`Julian Cockbain MA DPhil 0' Alison J HagueMA "
`Louise A Golding MA ‘
`Philip M Webber MA PhD 0
`Katherine F Mabey MA ‘
`Christopher R Davies 35c ’ ' Philip D Towler MA "
`Rebecca Gardner as: ’
`Matthew Hall BA M54: t
`Christopher R Goddard MA PnD '
`Alexander J Piésold as: " Andrea M Hughes BEng UM " Philip M Jeffrey 55: PhD '
`Elaine P Deyes as: '
`Catherine L Booth 35: PhD '
`’UK Chartered Patent Attorney. European Patent Attorney 'UK Registered Trade Mark Attorney, European Trade Mark Attorney
`
`Kirsteen H Gordon as: FhD ’
`Susannah Neath as: ‘
`Clare L Stoneman BA '
`Anna Leathley MEMO!” PhD r
`Andrew Chiva MSd '
`
`Offices in London Munish Brighton Oxford
`
`Page 4 of 21
`
`

`

`Page 5 of 21
`
`WO 2004/086451
`
`.
`
`PCT/IISZOII4/006456
`
`SPECIFICATION
`
`Plasma Generation Using Malti-Step
`I
`I
`Ionzzatwn
`
`,Haekgroundmf‘lnventionl
`
`[0001]
`
`Plasma is considered the fourth state of matter. A plasma is a collection of
`
`charged particles that move in random directions. A plasma is, on average,
`
`electrically neutral. One method of generating a plasma is to drive a current through
`
`a low—pressure gas between two conducting electrodes that are positioned parallel
`
`to each other. Once certain parameters are met, the gas "breaks down" to form the
`
`plasma. For example, a plasma can be generated by applying a potential of several
`
`(0002]
`
`kilovolts between two parallel conducting electrodes in an inert gas atmosphere
`(e.g., argon) at a pressure that is between about 10 '1 and l0 ‘2 Tori. (M WLnJL IO M J
`Plasma processes are widely used in many industries, such as the
`semiconductor manufacturing industry. For example, plasma etching is commonly
`used to etch substrate material and films deposited on substrates in the electronics
`
`I
`
`In“)
`
`industry. There are four basic types of plasma etching processes that are used to
`
`remove material from surfaces: sputter etching, pure chemical etching, ion energy
`driven etchingJand-lon inhibitor etching.
`
`[0003]
`
`Plasma sputtering is a technique that is widely used for depositing films on
`substrates and other work pieces. Sputtering is the physical ejection of atoms from
`a target surface and is sometimes referred to as physical vapor'deposition (PVD).
`ions, such as argon ions, are" generated and are then drawn out of the plasma and
`accelerated acr055 a cathode dark space. The target surface has a lower potential
`
`than the region In which the plasma ls formed. Therefore, the target surface attracts
`positive ions.
`
`Page 5 of 21
`
`

`

`Page 6 of 21
`
`Positive ions move towards the target with a high velocity and then impact
`the target and cause atoms to physically dislodge or sputter from the target surface.
`
`The sputtered atoms then propagate to a substrate or other work piece where they
`
`deposit a film of sputtered target material. The plasma is replenished by electron-
`
`ion pairs formed by the collision of neutral molecules with secondary electrons
`
`generated at the target surface.
`
`Reactive sputtering systems inject a reactive gas or mixture of reactive gases
`
`into the sputtering system. The reactive gases react with the target material either at
`
`the target surface or in the gas phase, resulting in the deposition of new compounds.
`
`10
`
`The pressure of the reactive gas can be varied to control the stoichiometry of the
`
`_ film. Reactive sputtering is useful for forming some types of molecular thin films.
`
`Magnetron sputtering systems use magnetic fields that are shaped to trap and
`
`concentrate Secondary electrons proximate to the target surface. The magnetic fields
`
`increase the densityof electrons and, therefore, increase the plasma density in a
`
`15
`
`region that is proximate to the target surface. The increased plasma density increases
`
`the sputter deposition rate.
`-JP 62-136573 describes a two step plasma generator in which a first plasma
`
`generating means excites atoms to a metastable state and a second plasma generating
`means generates a plasma from the metastable atom.
`
`20
`
`US 4007430 describes a continuous plasma laser which excites atoms to a
`
`metastable state. A magnetic field is applied axially along the chamber so as to
`
`increase the current path 'of electrons.
`
`According to the invention, there is provided a plasma generator comprising:
`
`an anode that is positioned in a plasma chamber;
`
`25
`
`a cathode assembly that is positioned adjacent to the anode in the plasma
`
`chamber;
`
`an excited atom source that receives ground state atoms from a feed gas
`source and that generates a volume of excited atoms between the anode and the
`
`, cathode from the feed gas; and
`
`30
`
`a power supply that generates an electric field between the anode and the
`
`cathode assembly, the electric field raising an energy of excited atoms in the volume
`
`of excited atoms so that at least a portion of the excited atoms in the volume of
`
`Page 6 of 21
`
`

`

`Page 7 of 21
`
`2a
`
`excited atoms is ionized, thereby generating a plasma between the anode and the
`
`cathode assembly; characterised in that
`
`the excited atom source comprises a magnet that is arranged to generate a
`
`magnetic field that traps electrons proximate to the ground state atoms.
`
`This invention is described with particularity in the detailed description
`
`which is given by way of example only. The above and further advantages of this
`
`invention may be better understood by referring to the following description in
`conjunction with the accompanying drawings, in which like numerals indicate like
`
`structural elements and features in various figures. The drawings are not necessarily
`
`10
`
`to scale, emphasis instead being placed upon illustrating the principles of the
`
`invention.
`
`FIG. 1 illustrates a cross-sectional view of a known plasma sputtering
`
`apparatus having a DC power supply.
`
`FIG. 2 illustrates a cross-sectional view of an embodiment of a plasma
`
`15
`
`generator that generates a plasma with a multi-step ionization process according to
`
`_
`
`the present invention.
`
`Page 7 of 21
`
`

`

`Page 8 of 21
`
`W.0 2004/086451
`
`PCT/[l82004/006456
`
`[0010}
`
`FIG. 3 illustrates a cross—sectional view of another embodiment of a plasma
`
`generator that generates a plasma with a multi-step ionization process according to
`
`the present invention.
`
`[0011]
`
`FIG. 4 illustrates a cross—sectional view of an embodiment of an excited atom
`
`generator that includes an excited atom source, such as a metastable atom source
`
`according to the present invention.
`
`[0012]
`
`FIG.' 5 illustrates a cross—sectional view ofW a chamber of an
`
`excited atom source such as a metastable atom sourceWW
`
`[0013}
`
`FIG. 6 illustrates a cross—sectional view of an excited atom source such as a
`metastable atom source according to the invention.
`
`[0014}
`
`Fig. 7 Is a perspective view of an excited atom source such as a metastable
`
`atom source according to one embodiment of the invention.
`
`[0015]
`
`FIG. 7A illustrates a cross-sectional view of the metastable atom source of FIG.
`
`7 that illustrates the magnetic field.
`
`[0016]
`
`FIG. 8 illustrates a cross—sectional view of another WWW excited
`
`atom source such as a metastable atom source Wren—thaw.
`
`[0017]
`
`FIG. 9 illustrates a cross—sectional View of another metastable atom source
`
`i
`
`[0018]
`
`FiG. 10 illustrates a cross—sectional view of another metastable atom source
`
`according to the invention
`
`[0019]
`
`FIG. 11 illustrates a cross~sectional view of another metastable atom source
`
`[0020]
`
`FIG. 12A through FIG. 12C illustrate various embodiments of_ electron/ion
`absorbers according to the invention.
`
`[0021]
`
`FIG. 13 is a flowchart of an illustrative process of generating a plasma with a
`
`multi—step ionization process according to the present invention.
`
`Page 8 of 21
`
`

`

`Page 9 of 21
`
`WO 2004/086451
`
`PCTfUSlilil4/0il6456
`
`u
`
`.l,
`
`..,
`
`{002 2]
`
`HO. 1 illustrates a cross—sectional view of a known plasma sputtering apparatus
`
`100 having a DC power supply 102. The known plasma sputtering apparatus 100
`
`includes a vacuum chamber 104 where a plasma 105 is generated. The vacuum
`
`chamber 104 can be coupled to ground. The vacuum chamber 104 is positioned in
`
`fluid communication with a vacuum pump 106 via a conduit 108 and a valve 109.
`
`The vacuum pump 106 is adapted to evacuate the vacuum chamber 104 to high
`
`(10 re.)
`
`vacuum. The pressure inside the vacuum chamber 104 is generally less than 10 "l
`~"Tart? A feed gas 110 from a feed gas source 11 i. such as an argon gas source. _is
`
`introduced into the vacuum chamber 104'through a gas inlet 112. The gas flow is
`
`controlled by a valve 113.
`
`[0023]
`
`The plasma sputtering apparatus 100 also includes a cathode assembly 114.
`The cathode assembly 114 is generally in the shape of a circular disk. The cathode
`
`assembly 114 can include a target 116. The cathode assembly 114 is electrically
`
`connected to a first terminal‘1 18 of the DC power supply 102 with an electrical
`transmission line 120. An insulator 122 isolates the electrical transmission line 120
`
`from a'wail of the vacuum chamber 104. An anode 124 is electrically connected to a
`
`second terminal 126 of the DC power supply 102 with an electrical transmission line
`
`127. An insulator 128 isolates the electrical transmission line 127 from the wall of
`
`the vacuum chamber 104. The anode 124 is positioned in the vacuum chamber 104
`
`proximate to the cathode assembly 114. An insulator 129‘ isolates the anode 124
`
`from the cathode assembly 114. The anode 124 and the second output 126 of the
`
`DC power supply 102 are coupled to ground in some systems.
`
`[002 4]
`
`The plasma sputtering apparatus 100 illustrates a magnetron sputtering system
`
`that includes a magnet 130 that generates a magnetic field 132 proximate to the
`target 1 16. The magnetic field 132 is strongest at the poles of‘the magnet 130 and
`weakest in the region 134. The magnetic field 132 is shaped to trap and
`
`
`concentrate secondary electrons proximate to the target surface. The magnetic field
`
`increases the de’n‘s‘ity ofTei‘ectFon‘s’ andffhereforETihcreases the plasma density in a
`
`region that is proximate to the target surface.
`
`Page 9 of 21
`
`

`

`Page 10 of 21
`
`WO 2004/086451
`
`PCTfliSZOfld/OOfidSfi
`
`and the diameter of the output 227 of the metastable atom source 204 is chosen so
`
`that a pressure differential is created that increases the generation rate of the
`
`metastable atoms 218 in the metastable atom source 204.
`
`[0043]
`
`The plasma chamber 230 confines the volume of metastable atoms 218. in one
`
`embodiment, the output of the metastable atom source 204 is positioned so as to
`
`direct the volume of metastable atoms 218 towards the cathode assembly 114. in
`
`one embodiment, the geometry of the plasma chamber 230 arid the cathode
`assembly 114 is chosen so that the metastable atoms reach the cathode assembly
`114 at a time that is much less than an average transition time of the metastable
`
`atoms to ground state atoms. in some embodiments. ground state atoms from the
`
`metastable atom source 204 gain energy in the metastable atom source 204, but do
`
`not actually become metastable atoms until they reach the plasma chamber 230.
`
`Ground state atoms from the metastable atom source 204 can become metastable
`
`atoms at any place along the path from the metastable atom source 204 to the
`
`cathode assembly 1 14. in some embodiments, the metastable atom source 204
`
`generates some excited atoms that are in excited states other than a metastable
`state.
`
`[004.4]
`
`The plasma chamber 230 is positioned in fluid communication with the vacuum
`
`pump 106 via the conduit 108 and the vacuum valve 109. The vacuum pump 106
`
`evacuates the plasma chamber 230 to high vacuum. The pressure inside the plasma
`' N (O a
`chamber 230 is generally maintained at less than 10 '1 Torrlfor plasma processing.
`in one embodiment, a feed gas (not shown) from a second feed gas source (not
`
`(
`
`i’ y
`
`shown), such as an argon gas source, is introduced into the plasma chamber 230
`
`through a gas inlet (not shown).
`
`[0045]
`
`in one embodiment, the power supply 201 is a pulsed power supply that is
`
`electrically coupled to the cathode assembly 1 14 with the electrical transmission
`line 120. in one embodiment, the duration .of the pulse is chosen to optimize a
`process parameter. in other embodiments. the power supply 201 ls-a RF power
`supply, an AC power supply, or a DC power supply. The isolator 122 insulates the
`
`electrical transmission line 120 from the plasma chamber 230. The second-output
`
`126 of the power supply 102 is electrically coupled to the anode 124 with the
`
`electrical transmission line 127. The isolator 128 insulates the electrical
`
`Page 10 of 21
`
`

`

`Page 11 of. 21
`
`WO 2004/086451
`
`23
`
`PCT/[ISZOfl4/006456 .
`
`[0103]
`
`Some of the ground state atoms 208 are directly ionized. which releases ions
`
`424 and electrons 426 into the stream of metastable atoms 218. Direct ionization
`
`occurs when bound electrons In an atom are ejected from that atom. The
`
`metastable atoms 2i 8, the free Ions 424 and electrons 426 then pass through the
`
`output 423 of the metastable atom source 402.
`
`[0104]
`
`FIG. 5 illustrates a cross—sectional view ofWWa chamber 450 of
`an excited atom source such as a metastable atom sourceWt
`inventicrr’ The chamber 450 Includes an input 452 having a first diameter 454. A
`gas line 456 from a gas source (not shown) is coupied to the input 452 of the
`
`chamber 450. The chamber 450 also includes an output 458 having a second
`diameter 460.
`
`[0105]
`
`in one embodiment, the first diameter 454 of the input 452 Is greater than the
`
`second diameter 460 of the output 458. The difference in the first 454 and the
`
`second diameters 460 creates a pressure differential between the input 452 and the
`
`output 458 'of the chamber 450. in one embodiment. the pressure differential is
`
`chosen so that the pressure in the chamber 450 is increased. The increase in
`
`pressure can improve the efficiency of the generation of the metastable atoms 213
`
`from the ground state atoms 208. in one embodiment, the ratio of the first diameter
`
`454 to the second diameter 460 is chosen to optimize the excitation process in the
`
`chamber 450. In addition, the pressure differential can increase the velocity of the
`
`metastable atoms 2i 8 flowinthhrough the output 458.
`
`[01 06]
`
`FIG. 6 illustrates a cross~sectionai view of an embodiment of an excited atom
`
`source such as a metastable atom source 500 according to the invention. The
`
`metastable atom source 500 is similar to the metastable atom source 402 of FIG. 4.
`
`The metastable atom source 500 includes a Chamber 502. Themetastable atom
`
`source 500 also includes first 504a, b and second magnets 5063,'b that create
`
`magnetic fields 508a, b through the chamber 502.
`
`Page 11 of 21
`
`

`

`Page 12 of 21
`
`WO 2004/086451
`
`26
`
`PCT/IlSZOfi4/iliifi456
`
`[0114]
`
`A second electrode 560 is disposed inside the chamber 554 proximate to the
`
`first electrode 556. in one embodiment, the first electrode 556 is a cathode and the
`
`second electrode 560 is an anode. A first input terminal 562 couples the first
`
`electrode 556 to a powar supply (not shown). A second input terminal 564 couples
`
`the second electrode 560 to the power supply.
`
`[0115]
`
`in one embodiment, magnets 566a—d are positioned on the top surface 568 of
`
`the first electrode 556. in this embodiment, magnets S70a~d are also positioned in
`
`the bottom surface 572 of the second electrode 560 opposite to the magnets 566a~
`
`d. The magnets 566a—d trap electrons and increase the probability that electrons
`
`will collide with ground state atoms and generate metastable atoms. In one
`
`embodiment, the metastable atom source 550 includes at least one mirror (not
`
`shown) that is positioned so as to reflect light that is generated when excited and
`
`metastable atoms decay to the ground state.
`
`[01 l 6}
`
`FIG. 7A illustrates a cross—sectional View of the metastable atom source 550 of
`
`FIG. 7 illustrating'the magnetic field 574. The magnets 566a~d, 570a-d create a
`
`magnetic field 574 that substantially traps and accelerates electrons (not shown) in
`
`the chamber 554. The trapped electrons (not shown) collide with the ground state
`
`atoms (not shown), thereby raising the energy of the ground state atoms to a
`
`metastable state. The metastable atoms (not shown) exit the chamber 554 through
`one or more gas outputs 576.
`
`[0117]
`
`The operation of the metastable atom source 550 is similar to the operation of
`
`the metastable atom source 500 of HQ. 6. However. in this embodiment, the
`
`metastable atom source 550 does not include an electron/ion absorber 536. Thus, a
`
`small volume of ions and/or electrons that are not trapped by the magnetic field
`
`574 will‘likeiy exit the chamber 554 of the metastable atom source 550 through the
`
`gas outputs 576.
`
`[Oi T3}
`
`FIG. 8 illustrates a cross—sectional view of another embodiment-ow excited
`
`atom source such as a metastable atom source 600 {recording-MW The
`metastable atom source 600 includes a chamber 602. The metastable atom source
`
`600 also includes an electron gun 604 and an electron trap 606. The electron gun
`
`604 includes a power supply 626 that is coupled to a filament electrode 628. The
`
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`power supply 626 can be any type of power suppiy. such as a DC, an AC, a RF, or a
`
`pulsed power supply. A first output 630 of the power supply 626 is coupled to a
`
`first terminal 632 of the filament electrode 628 with a first transmission line 634. A
`
`Second output 636 of the power supply 626 is coupled to a second terminal 638 of
`
`the filament electrode 628 with a second transmission line 640.
`
`[0119]
`
`The electron gun 604 also includes an acceleration grid 642 that is adapted to
`
`accelerate the electrons 608 that are emitted by the filament electrode 628. An
`input %2’of the acceleration grid 642 is coupled to a first output 644 of a power
`supply 646. In one embodiment, the power supply 646 is a DC power supply or a
`
`pulsed power supply. The first output 644 of the power supply 646 couples a
`flat” the acceleration grid 642. The positive voltage
`accelerates the negatively charged electrons towards the acceleration grid 642. in
`
`one embodiment, a second output 648 of the power supply 646 is coupled to the
`
`(705th
`
`second '
`
`636 of the power supply %. However, many different power supply -
`
`configurations are possible.
`
`[01 20]
`
`A gas line 610 is coupled to an input 612 of the chamber 602. An output 614 of
`
`the chamber 602 is coupled to an input 616 of an electron/ion absorber 618. in one
`
`embodiment, a diameter 622 of the input 612 of the chamber 602 and a diameter
`
`624 of the output 614 of the chamber 602 are chosen to optimize the process of
`
`generating the metastable atoms 218.
`
`[0121}
`
`in operation, ground state atoms 208 from the gas source (not shown) tiow into
`
`the chamber 602 through the input 612. The ground state atoms 208 flow into a
`
`region 649 proximate to the electron gun 604. The electron gun 604 generates and
`
`accelerates electrons 608 into the region 649. A portion of the ground state atoms
`
`208 that are injected through the region 649 collide with the electrons 608 and are
`energized to a metastable state. Some of those ground state atoms 208 are
`energized to the point of ionization and release free ions 424 and electrons 426
`
`into the stream of metastable atoms 218. Others of those ground state atoms 208
`
`are energized to excited states other than a metastable state.
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`[Oi 22]
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`The electron trap 606 traps electrons 608 that are generated and accelerated by
`
`the electron gun 604. In one embodiment, the electron trap 606 is negatively
`biased. In this embodiment. ions 424 in the chamber 602 impact the surface of the
`
`electron trap 606 and generate secondary electrons from the surface of the electron
`trap 606. in another embodiment, the electron trap 606 is positively biased. in this
`
`embodiment, electrons 608 in the chamber 602 are further accelerated and trapped
`
`by the electron trap 606.
`
`'
`
`[0123]
`
`The metastable atoms 218, the ground state atoms 208, the ions 424 and
`
`electrons 426 then pass through the output 6i 4 of the chamber 602. The
`
`electron/ion absorber 618 receives the metastable atoms 218, ground state atoms
`208, ions 424 and electrons 426 through the input 616. The electron/ion absorber
`
`6i 8 traps the ions 424 and the electrons 426 and allows the metastable atoms 218
`
`and the ground state atoms 208 to pass through the output 620.
`
`[0124]
`
`FIG. 9 illustrates a cross-sectional view of another metastable atom source 650
`
`W. The metastable atom source 650 includes a chamber
`652. in one embodiment, the chamber 652 is formed of a nonoconductlng pipe or a
`
`dielectric tube. The metastable atom source 650 also includes an inductive coii 654
`
`that surrounds the chamber 652. The inductive coll 654 is adapted to inductively
`
`couple energy into the chamber 652.
`
`[0125]
`
`A gas line 656 is coupled to an input 653 of the chamber 652. An output 660 of
`
`the chamber 652 is coupled to an input 662 of a electron/ion absorber 664. The
`
`metastable atoms 2i 8 pass through an output 666 of the electron/ion absorber
`664. in one embodiment, a diameter 668 of the input 658 of the chamber 652 and a
`
`diameter 670 of the output 660 of the chamber 652 are chosen to optimize the
`process of generating the metastable atoms 218.
`
`[0126]
`
`The metastable atom source 650 includes a power supply 672. Any type of
`
`'power supply can be used, such as a DC, an AC, a RF, or a pulsed power supply. A
`
`first output 674 of the power supply 672 is coupled to a first terminal 676 of the
`
`inductive coil 654 with a first transmission line 678. A second output 680 of the
`
`power supply 672 is coupled to a second terminal 682 of the inductive coii 654 with
`a second transmission line 684.
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`the pressure in the region 7i0 can increase the efficiency of the excitation process
`
`and, therefore the efficiency of generating the metastable atoms.
`
`[013]]
`
`A power supply (not shown) is electrically connected between the first 704 and
`
`the second cylindrical electrodes 706. in one embodiment, one terminal of the
`
`power supply is coupled to ground. In this embodiment, one of the first 704 and
`
`second cylindrical electrodes 706 is also coupled to ground (not shown).
`
`[01 32]
`
`lo—ene—embod-imentlThe metastable atom source 700 includes electromagnetic
`coils 712, 714. The electromagnetic coils 712. 7l4 generate a magnetic field 7) 6
`
`having magnetic field lines 718, 720. The magnetic field 7i 6 traps electrons
`
`proximate to the region 710. The trapped electrons assist in trapping ions
`
`proximate to the region 710. in other embodiments, the metastable atom source
`700 includes magnets (not shown).
`
`[0133]
`
`A gas line (not shown) is coupled to an input 722 of the chamber 702. An
`
`output 724 of the chamber 702 is coupled to an input 726 of an electron/ion
`
`absorber 728. The electron/ion absorber 728 passes the metastable atoms 218
`
`through an output 730.
`
`'[0134]
`
`in operation, ground state atoms 208 from the gas source (not shown) flow into
`
`the chamber 702 through the input 722. The ground state atoms 208 then flow into
`
`the region 710. The power supply (not shown) generates a voltage between the first
`
`_
`
`704 and the second cylindrical electrodes 706. The voltage creates an electric field
`
`that raises the energy of the ground state atoms 2.08. A portion of the ground state
`
`atoms 208 that are injected through the region 710 are energized to a metastable
`
`state. A fraction of the ground state atoms 208 are ionized and release free ions
`
`424 and electrons 426 into the stream of metastable atoms 218. A portion of the
`
`ground state atoms 208 in the region 710 can be excited to states other than a
`metastable state.
`)
`
`[0135)
`
`The metastable atoms 218, the ground state atoms 208, the ions 424 and
`
`electrons 426 then pass through the output 724 of the chamber 702. The
`
`electron/ion absorber 728 receives the metastable atoms 218, the ground state
`
`atoms 208, the ions 424 and the electrons 426 through the input 726. The
`
`electron/Ion absorber 728 traps the ions 424 and the electrons 426 and allows the
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`metastable atoms 218 and the ground state atoms 208 to pass through the output
`730.
`
`[0136]
`
`in other embodiments of the invention, the ground state atoms 208 are
`
`energized to a metastable state by using an energy source, such as a DC plasma
`
`'source, a radio frequency (RF) plasma source, an ultraviolet (UV) radiation source,
`
`an X—ray radiation source, an electron beam radiation source, an ion beam radiation
`
`source, an inductively coupled plasma (ICP) source, a capacitively coupled plasm