Etching method and apparatus
First Claim
1. An etching method for etching a plurality of layers to be etched having a different index of refraction, comprising:
- illuminating the layers to be etched by two coherent lights each having a different wavelength;
observing two interfered lights generated by the illuminating two different lights reflected on a boundary between the layers to be etched; and
based on the frequency of either of the two observed interfered lights whichever meeting predetermined requirements, measuring the etching depth.
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Accused Products
Abstract
A to-be-etched substrate is illuminated by two lights each having a different wavelength coming from a light source in a light source detector section. The lights are reflected on the to-be-etched substrate. The two reflected lights as a result of reflection on the to-be-etched substrate each include an interfered light, which is generated by the lights reflected on the surface of the layer to be etched, and a boundary between the layers to be etched. A detector in a light source detector section converts the intensity of the received two interfered lights into electric signals for output to a control section. The control section calculates the etching speed from the frequency of either of the two interfered lights whichever having the larger amplitude. Based on thus calculated etching speed and the time taken for the etching operation, the etching depth is calculated.
13 Citations
17 Claims
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1. An etching method for etching a plurality of layers to be etched having a different index of refraction, comprising:
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illuminating the layers to be etched by two coherent lights each having a different wavelength;
observing two interfered lights generated by the illuminating two different lights reflected on a boundary between the layers to be etched; and
based on the frequency of either of the two observed interfered lights whichever meeting predetermined requirements, measuring the etching depth. - View Dependent Claims (2, 3, 4, 5)
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6. An etching method for etching a plurality of layers to be etched varying in index of refraction, comprising:
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illuminating the layers to be etched by coherent lights of the same wavelength coming from two different directions;
observing two interfered lights generated by the illuminating lights coming from the two different directions and being reflected on a boundary between the layers to be etched; and
based on the frequency of either of the two observed interfered lights whichever meeting predetermined requirements, measuring the etching depth. - View Dependent Claims (8)
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7. The etching method of 6 wherein, one of the two different directions is vertical to the surface of the layers to be etched,
of adjacent layers of the plurality of layers to be etched whose boundary has a maximum reflection among those of boundaries of the other adjacent layers of the plurality of layers, a light illumination side layer of the adjacent layers whose boundary has the maximum reflection has an index of refraction lower than that of the other of the adjacent layers to be etched, and in the light illumination side layer, an angle θ - between a direction vertical to a surface of layers to be etched and a second direction being the other of the two different directions does not satisfy an equation of cos θ
=2 nL/(2 nL+λ
N2),where L denotes a thickness of the light illumination side layer to be etched, n denotes the index of refraction thereof, λ
is the wavelength of the coherent lights, and N2 is an odd natural number.
- between a direction vertical to a surface of layers to be etched and a second direction being the other of the two different directions does not satisfy an equation of cos θ
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9. An etching apparatus for etching a plurality of layers to be etched varying in index of refraction, comprising:
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a light emission section for emitting two coherent lightseach having a different wavelength;
an optical system for illuminating the layers to be etched by the two different lights emitted from the light emission section;
a detector for receiving two interfered lights generated by the two different lights that illuminate the layers to be etched by the optical system, and that are reflected on a boundary between the layers to be etched; and
a measurement section for measuring the etching depth based on the frequency of either of the two interfered lights received by the detector whichever meeting predetermined requirements. - View Dependent Claims (10, 11, 12, 13)
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14. An etching apparatus for etching a plurality of layers to be etched varying in index of refraction, comprising:
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a light emission section for emitting coherent lights of the same wavelength;
an optical system for illuminating the layers to be etched by the lights emitted from the light emission section from two different directions;
a detector for receiving two interfered lights generated by the lights from the two different directions that illuminate the layers to be etched by the optical system, and that are reflected on a boundary between the layers to be etched; and
a measurement section for measuring the etching depth based on the frequency of either of the two interfered lights received by the detector whichever meeting predetermined requirements. - View Dependent Claims (15, 16, 17)
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Specification