EP0320425A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Plasma amplified photoelectron process endpoint detection apparatus
Assignee: International Business Machines Corp
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Filing: 1988-10-25
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Granted: —
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Expires: 2008-10-25
Abstract
Abstract A plasma processing apparatus and process endpoint detection method comprising a plasma chamber for processing an item that has a first portion of a first material and a second portion of a second material, with the first and second materials having different work functions, and means for generating a plasma in the plasma chamber, with the plasma generating means including at least a pair of RF-power electrodes with one of them being excited by an RF excitation frequency. The apparatus further includes means for generating and ejecting electrons from said second material only when the second material is exposed to the plasma, and means for increasing the energies of these generated electrons and accelerating these electrons into the etching plasma with sufficient energy to generate secondary electrons in the plasma. The apparatus further includes means for receiving a plasma discharge voltage signal, means for filtering the discharge electrical voltage signal to remove the RF excitation frequency and any DC components therein, and means for amplifying the natural frequencies of excitation and decay of the plasma discharge voltage perturbation signal, to thereby detect the processing endpoint. In a preferred embodiment, the electron energy increasing and accelerating means comprises means for generating an electrode voltage sheath, and means for generating the electrons within this voltage sheath to thereby accelerate the electrons into the plasma. The electron generating means comprises means for directing a beam of photons in a selected energy range onto the item to be processed, which energy range is not sufficient to eject photoelectrons from the first material, but is high enough to generate photoelectrons from areas of exposed second material.
Inventors
- 👤 John Howard Keller
- 👤 Gary Stewart Selwyn
- 👤 Joythi Singh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 19:33
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
161 words
A plasma processing apparatus comprising: a plasma generation chamber for processing an item that includes a first portion of a first material and a second portion of a second material, with said first and second materials having different work functions; means for generating a plasma in said plasma chamber, said plasma generating means including an RF-powered electrode excited by an RF excitation frequency; means for generating and ejecting electrons only when said second material is exposed to said plasma; means for increasing the energies of said generated electrons and accelerating said electrons into said plasma, with sufficient energy to thereby generate secondary electrons in said plasma; means for receiving a plasma RF discharge voltage signal; means for filtering said plasma RF discharge voltage signal to remove the RF excitation frequency therefrom; and means for amplifying the natural frequencies of excitation and decay in the plasma discharge voltage signal in the plasma discharge to thereby detect the process endpoint or surface condition.
Claim 2
Dependent Claim
161 words
A plasma processing apparatus comprising: a plasma generation chamber for processing an item that includes a first portion of a first material and a second portion of a second material, with said first and second materials having different work functions; means for generating a plasma in said plasma chamber, said plasma generating means including an RF-powered electrode excited by an RF excitation frequency; means for generating and ejecting electrons only when said second material is exposed to said plasma; means for increasing the energies of said generated electrons and accelerating said electrons into said plasma, with sufficient energy to thereby generate secondary electrons in said plasma; means for receiving a plasma RF discharge voltage signal; means for filtering said plasma RF discharge voltage signal to remove the RF excitation frequency therefrom; and means for amplifying the natural frequencies of excitation and decay in the plasma discharge voltage signal in the plasma discharge to thereby detect the process endpoint or surface condition.
Claim 3
Dependent Claim
41 words
An apparatus as defined in claim 1, wherein said electron energy increasing and accelerating means comprises means for generating an electrode voltage sheath; and means for generating said electrons within said voltage sheath to thereby accelerate said electrons into said plasma.
Claim 4
Dependent Claim
55 words
An apparatus as defined in claim 2, wherein said electron generating means comprises means for directing a beam of photons in a selected energy range on to said item, which energy range is not sufficient to eject electrons from said first material, but is high enough to generate electrons from areas of exposed second material.
Claim 5
Dependent Claim
37 words
An apparatus as defined in claim 1, wherein said filtering means comprises a capacitor for blocking out any DC signal components; and notch filter means for removing any RF excitation signal harmonics from said discharge voltage signal.
Claim 6
Dependent Claim
25 words
An apparatus as defined in claim 4, wherein said filtering means includes means for amplifying said filtered signal in the frequency range of 0.3-7 MHz.
Claim 7
Dependent Claim
17 words
An apparatus as defined in claim 2, further comprising means for integrating said filtered and amplified signal.
Claim 8
Dependent Claim
30 words
An apparatus as defined in claim 1, wherein said plasma generation chamber is a dry etching chamber; and wherein said plasma generating means comprises means for generating an etching plasma.
Claim 9
Dependent Claim
29 words
An apparatus as defined in claim 1, wherein said plasma generation chamber is a deposition chamber; and wherein said plasma generating means comprises means for generating a deposition plasma.
Claim 10
Independent Claim
147 words
A method for detecting the endpoint in a plasma process comprising the steps of: disposing an item to be processed in a plasma chamber, said item including a first portion of a first material and a second portion of a second material, with said first material having a greater work function than said second material; generating by means of an RF electrode excited by an RF excitation frequency a plasma in said plasma chamber to process said item; generating and ejecting electrons from said second material only when said second material is exposed to said plasma; accelerating said generated electrons into said plasma with a sufficient energy to thereby generate secondary electrons in said plasma; receiving a plasma discharge voltage signal; filtering and amplifying the plasma discharge voltage signal to monitor the natural frequencies of excitation and decay of the plasma, to thereby determine the process endpoint.
Claim 11
Independent Claim
147 words
A method for detecting the endpoint in a plasma process comprising the steps of: disposing an item to be processed in a plasma chamber, said item including a first portion of a first material and a second portion of a second material, with said first material having a greater work function than said second material; generating by means of an RF electrode excited by an RF excitation frequency a plasma in said plasma chamber to process said item; generating and ejecting electrons from said second material only when said second material is exposed to said plasma; accelerating said generated electrons into said plasma with a sufficient energy to thereby generate secondary electrons in said plasma; receiving a plasma discharge voltage signal; filtering and amplifying the plasma discharge voltage signal to monitor the natural frequencies of excitation and decay of the plasma, to thereby determine the process endpoint.
Claim 12
Dependent Claim
39 words
A method as defined in claim 9, wherein said accelerating step comprises the steps of generating a voltage sheath adjacent to said RF electrode; and generating and ejecting said electrons within said voltage sheath to thereby accelerate said electrons.
Claim 13
Dependent Claim
47 words
A method as defined in claim 10, wherein said filtering and amplifying step includes the step of filtering out said RF excitation frequency from said plasma discharge voltage signal and amplifying the band of frequencies containing the natural frequencies of excitation and decay of the plasma discharge.
Claim 14
Dependent Claim
37 words
A method as defined in claim 9, wherein said disposing step comprises the step of disposing said item in a dry etching chamber; and wherein said plasma generating step comprises the step of generating an etching plasma.
Claim 15
Dependent Claim
36 words
A method as defined in claim 9, wherein said disposing step comprises the step of disposing said item in a deposition chamber; and wherein said plasma generating step comprises the step of generating a deposition plasma.
Claim 16
Independent Claim
203 words
A method for detecting the endpoint in a plasma etching process comprising the steps of: disposing an item to be etched in a dry etching chamber, said item including a top layer of a first material disposed over a second layer of a second material, with said first and second materials having different work functions; generating by means of an RF excitation frequency an etching plasma in said etching chamber to etch said item; directing a beam of energy in a selected energy range on to said item, which energy range is not sufficient to eject photoelectrons from one of said first or second materials on said item, but is high enough to eject photoelectrons into said plasma from the other of said first or second materials; ejecting photoelectrons by means of said beam of energy when said other material is exposed by said etching process; accelerating said ejected photoelectrons into said with a sufficient energy to thereby generate secondary electrons in said plasma; receiving a plasma discharge voltage signal; filtering the plasma discharge voltage signal to remove said RF excitation frequency; and amplifying the natural frequencies of excitation and decay of the filtered plasma voltage discharge signal to detect the etch endpoint.
Claim 17
Independent Claim
203 words
A method for detecting the endpoint in a plasma etching process comprising the steps of: disposing an item to be etched in a dry etching chamber, said item including a top layer of a first material disposed over a second layer of a second material, with said first and second materials having different work functions; generating by means of an RF excitation frequency an etching plasma in said etching chamber to etch said item; directing a beam of energy in a selected energy range on to said item, which energy range is not sufficient to eject photoelectrons from one of said first or second materials on said item, but is high enough to eject photoelectrons into said plasma from the other of said first or second materials; ejecting photoelectrons by means of said beam of energy when said other material is exposed by said etching process; accelerating said ejected photoelectrons into said with a sufficient energy to thereby generate secondary electrons in said plasma; receiving a plasma discharge voltage signal; filtering the plasma discharge voltage signal to remove said RF excitation frequency; and amplifying the natural frequencies of excitation and decay of the filtered plasma voltage discharge signal to detect the etch endpoint.
Claim 18
Dependent Claim
32 words
A method as defined in claim 14, wherein said filtering step comprises the step of filtering out any RF excitation frequency harmonics and any D.C. components from said plasma discharge voltage signal.
References Cited (Backward Citations)
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