Detection of interfaces with atomic resolution during material processing by optical second harmonic generation
AssigneeInternational Business Machines Corporation
InventorsTony F. Heinz, Gary S. Selwyn, Syothi Singh, John A. Spinetti, Jr.
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Abstract
A technique for observing optical second harmonic generation effect at a surface of a material during processing thereof, particularly in the presence of a plasma, for controlling the processing of the material. A preferred form of the apparatus and method includes a combination of spectral, spatial, polarization and temporal filtering to allow observation of optical second harmonic generation and control of processing of the material with processes such as reactive ion etching to a high degree of resolution.
Claims20
A method of observing the surface of a material during processing of the material in the presence without control or limitation of ambient radiation produced by said processing, said method including the steps of
- directing coherent radiation of a first frequency toward said surface of said material,
- filtering said coherent radiation to pass substantially only radiation at said first frequency and to block substantially all radiation at a second frequency, said second frequency being twice said first frequency,
- illuminating said surface with said coherent radiation for an interval of time,
- observing radiation from said surface at said second frequency for a period of time beginning slightly subsequent to the beginning of said interval of time of said illuminating step, and
- controlling said processing in response to a change in radiation from said surface at said second frequency.
A method of end-point detection in a process of etching a layer of material including the steps of
- directing coherent radiation of a first frequency toward said surface of said material,
- filtering said coherent radiation to pass substantially only radiation at said first frequency and to block substantially all radiation at a second frequency, said second frequency being twice said first frequency,
- illuminating said surface with said coherent radiation for an interval of time,
- observing radiation from said surface at said second frequency for a period of time beginning slightly subsequent to the beginning of said interval of time of said illuminating step, and
- controlling said processing in response to a change in radiation from said surface at said second frequency.
Dependencies are inferred from the claim text.