Method and apparatus for real-time, in-situ endpoint detection and closed loop etch process control
First Claim
1. An apparatus for real-time in-situ detection of an etching endpoint of a film on a substrate during etching of the film, said apparatus comprising:
- a) means for providing a first excitation beam of light, the first light beam having a wavelength and furthermore substantially containing only a first harmonic component of light at that wavelength;
b) means for directing the first light beam at a prescribed incident angle to an interface between the film and the substrate, the first light beam being reflected off the interface to thereby provide a second light beam, the second light beam containing the first harmonic component of the first light beam and a generated second harmonic component, the second harmonic component thereof being generated as a result of the reflection of the first light beam off the interface;
c) means for detecting the generated second harmonic component of the first light beam, said detecting means providing a first output signal representative of the detected second harmonic component;
d) means for producing a generated second harmonic component reference of the first light beam, said second harmonic component reference producing means providing a second output signal representative of a generated second harmonic component reference, wherein said second harmonic component reference means comprises i) a beam splitter positioned intermediate said first light beam providing means and said directing means for partially reflecting and partially transmitting the first light beam, the partially reflected portion of the first light beam providing a fourth light beam, wherein the partially transmitted portion of the first light beam is received by said directing means, ii) a third interference filter for filtering the fourth light beam to remove substantially all but a first harmonic component of the fourth light beam, iii) a reference medium for receiving the fourth light beam on a first side thereof and providing a fifth light beam exiting from a second side thereof, the fifth light beam containing the first harmonic component and a generated reference second harmonic component, iv) a specially coated dichroic mirror for efficiently reflecting the generated reference second harmonic component and efficiently transmitting the first harmonic component of the fifth light beam, the reflected portion of the fifth light beam providing a sixth light beam, v) a fourth interference filter for further removing any residual first harmonic component light from the sixth light beam to provide a seventh light beam, the seventh light beam containing substantially the generated reference second harmonic component of the fifth light beam, and vi) a second monochrometer equipped with a photomultiplier tube for receiving the seventh light beam, said second monochrometer providing the second output signal representative of the second harmonic component reference; and
e) means responsive to the first and second output signals for normalizing the generated second harmonic component of the first light beam detected by said detection means in real-time, said real-time normalizing means providing a third output signal representative of an occurrence of a prescribed change in the normalized detected second harmonic component of the first light beam, the prescribed change corresponding to an etching end-point of the film on the substrate.
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Abstract
A method and apparatus for detecting an etching endpoint of a film on a substrate whereby a first excitation beam of light having a prescribed wavelength is provided, the first light beam substantially containing only a first harmonic component of light at that wavelength. The first light beam is directed at a prescribed incident angle to an interface between the film and the substrate, the first light beam being reflected off the interface to thereby provide a second light beam, the second light beam containing the first harmonic component of the first light beam and a generated second harmonic component. The generated second harmonic component is detected and a first output signal representative thereof is provided. A generated second harmonic component reference of the first light beam is produced and a second output signal representative of a generated second harmonic component reference is provided. The detected second harmonic component of the first light beam is normalized, as a function of the first and second output signals, in real-time, and a third output signal representative of an occurrence of a prescribed change in the normalized detected second harmonic component is provided. The prescribed change corresponds to the etching endpoint of the film on the substrate.
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Citations
40 Claims
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1. An apparatus for real-time in-situ detection of an etching endpoint of a film on a substrate during etching of the film, said apparatus comprising:
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a) means for providing a first excitation beam of light, the first light beam having a wavelength and furthermore substantially containing only a first harmonic component of light at that wavelength; b) means for directing the first light beam at a prescribed incident angle to an interface between the film and the substrate, the first light beam being reflected off the interface to thereby provide a second light beam, the second light beam containing the first harmonic component of the first light beam and a generated second harmonic component, the second harmonic component thereof being generated as a result of the reflection of the first light beam off the interface; c) means for detecting the generated second harmonic component of the first light beam, said detecting means providing a first output signal representative of the detected second harmonic component; d) means for producing a generated second harmonic component reference of the first light beam, said second harmonic component reference producing means providing a second output signal representative of a generated second harmonic component reference, wherein said second harmonic component reference means comprises i) a beam splitter positioned intermediate said first light beam providing means and said directing means for partially reflecting and partially transmitting the first light beam, the partially reflected portion of the first light beam providing a fourth light beam, wherein the partially transmitted portion of the first light beam is received by said directing means, ii) a third interference filter for filtering the fourth light beam to remove substantially all but a first harmonic component of the fourth light beam, iii) a reference medium for receiving the fourth light beam on a first side thereof and providing a fifth light beam exiting from a second side thereof, the fifth light beam containing the first harmonic component and a generated reference second harmonic component, iv) a specially coated dichroic mirror for efficiently reflecting the generated reference second harmonic component and efficiently transmitting the first harmonic component of the fifth light beam, the reflected portion of the fifth light beam providing a sixth light beam, v) a fourth interference filter for further removing any residual first harmonic component light from the sixth light beam to provide a seventh light beam, the seventh light beam containing substantially the generated reference second harmonic component of the fifth light beam, and vi) a second monochrometer equipped with a photomultiplier tube for receiving the seventh light beam, said second monochrometer providing the second output signal representative of the second harmonic component reference; and e) means responsive to the first and second output signals for normalizing the generated second harmonic component of the first light beam detected by said detection means in real-time, said real-time normalizing means providing a third output signal representative of an occurrence of a prescribed change in the normalized detected second harmonic component of the first light beam, the prescribed change corresponding to an etching end-point of the film on the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for real-time in-situ detection of an etching endpoint of a film on a substrate during etching of the film, said method comprising the steps of:
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a) providing a first excitation beam of light, the first light beam having a wavelength and furthermore substantially containing only a first harmonic component of light at that wavelength; b) directing the first light beam at a prescribed incident angle to an interface between the film and the substrate, the first light beam being reflected off the interface to thereby provide a second light beam, the second light beam containing the first harmonic component of the first light beam and a generated second harmonic component, the second harmonic component thereof being generated as a result of the reflection of the first light beam off the interface; c) detecting the generating second harmonic component of the first light beam and providing a first output signal representative of the detected second harmonic component; d) producing a generated second harmonic component reference of the first light beam and providing a second output signal representative of a generated second harmonic component reference, wherein producing the generated second harmonic component reference further comprises i) providing a beam splitter positioned for partially reflecting and partially transmitting the first light beam, the partially reflected portion of the first light beam providing a fourth light beam, ii) providing a third interference filter for filtering the fourth light beam to remove substantially all but a first harmonic component of the fourth light beam, iii) providing a reference medium for receiving the fourth light beam on a first side thereof to provide a fifth light beam exiting from a second side thereof, the fifth light beam containing the first harmonic component and a generated reference second harmonic component, iv) providing a specially coated dichroic mirror for efficiently reflecting the generated reference second harmonic component and efficiently transmitting the first harmonic component of the fifth light beam, the reflected portion of the fifth light beam providing a sixth light beam, v) providing a fourth interference filter for further removing any residual first harmonic component light from the sixth light beam to provide a seventh light beam, the seventh light beam containing substantially the generated reference second harmonic component of the fifth light beam, and vi) providing a second monochrometer equipped with a photomultiplier tube for receiving the seventh light beam, the second monochrometer providing the second output signal representative of the second harmonic component reference; and e) normalizing the generated second harmonic component of the first light beam detected by said detection means in real-time as a function of the first and second output signals, said normalizing step further providing a third output signal representative of an occurrence of a prescribed change in the normalized detected second harmonic component of the first light beam, the prescribed change corresponding to an etching endpoint of the film on the substrate. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification