Atomic layer etch process using an electron beam
First Claim
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1. A method of removing an overlying film from a workpiece, comprising:
- supporting the workpiece in a chamber;
coupling an RF bias voltage to said workpiece;
(A) performing a passivation process for a time duration corresponding to a desired thickness of a layer of said overlying film to be passivated, said passivation process comprising;
introducing a passivation process gas into said chamber;
generating a plasma in said chamber for passivation, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
controlling said RF bias voltage to set energy of ions in said chamber to a first ion energy level less than a first minimum ion energy required for etching said overlying film;
(B) performing an etching process by;
introducing an etching process gas into said chamber;
generating a plasma in said chamber for etching, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
controlling said RF bias voltage to set energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy;
wherein said controlling said RF bias voltage to set energy of ions to a first ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform; and
wherein said controlling said RF bias voltage to set energy of ions to a second ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform.
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Abstract
Atomic layer etching using alternating passivation and etching processes is performed with an electron beam plasma source, in which the ion energy is set to a low level below the etch threshold of the material to be etched during passivation and to a higher level above the etch threshold during etching but below the etch threshold of the unpassivated material.
6 Citations
16 Claims
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1. A method of removing an overlying film from a workpiece, comprising:
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supporting the workpiece in a chamber; coupling an RF bias voltage to said workpiece; (A) performing a passivation process for a time duration corresponding to a desired thickness of a layer of said overlying film to be passivated, said passivation process comprising; introducing a passivation process gas into said chamber; generating a plasma in said chamber for passivation, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator; controlling said RF bias voltage to set energy of ions in said chamber to a first ion energy level less than a first minimum ion energy required for etching said overlying film; (B) performing an etching process by; introducing an etching process gas into said chamber; generating a plasma in said chamber for etching, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator; controlling said RF bias voltage to set energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy; wherein said controlling said RF bias voltage to set energy of ions to a first ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform; and wherein said controlling said RF bias voltage to set energy of ions to a second ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of performing atomic layer etching of an overlying film on a workpiece, comprising:
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coupling an RF bias voltage to said workpiece; passivating a predetermined thickness of a layer of said overlying film, comprising introducing into said chamber a gas containing a passivation species and generating a plasma in said chamber for passivation by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator; etching the predetermined thickness of said layer, comprising introducing into said chamber a gas containing an etch species and generating a plasma in said chamber for etching by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator; during said passivating, setting energy of ions in said chamber to a first ion energy level less than a first minimum ion energy for etching said layer by conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of at least 50% of an RF cycle of said RF waveform; during said etching, setting energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy by conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of at least 50% of an RF cycle of said RF waveform. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of removing an overlying film on a workpiece in a chamber, comprising:
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performing alternating operations of passivating and etching; wherein said passivating comprises;
introducing into said chamber a gas containing a passivation species and generating a plasma in said chamber for passivation by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;wherein said etching comprises;
introducing into said chamber a gas containing an etch species and generating a plasma in said chamber for etching by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;during said passivating, tailoring RF bias power to a waveform in which RF voltage is at a level corresponding to a first ion energy level less than an etch threshold of said overlying film for a duration of at least 50% of an RF cycle of said waveform; and during said etching, tailoring RF bias power to a waveform in which RF voltage is at a level corresponding to a second ion energy level exceeding an etch threshold of said overlying film for a duration of at least 50% of an RF cycle of said waveform. - View Dependent Claims (15, 16)
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Specification