Ellipsometric control of material growth
AssigneeBell Communications Research, Inc.
InventorsDavid E. Aspnes, William E. Quinn
Life of this patent
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Abstract
A method and apparatus for controlling the growth of a multispecies film. During the film growth, an ellipsometer continuously monitors the surface on which the film is growing. The ellipsometer data is used to calculate the effective complex dielectric constant of the thin-film/substrate structure. A sequence of such data is used in a model calculation to determine the composition of the top portion of the thin film. The measured composition is compared with the target composition and the amount supplied of one of the species is correspondingly changed.
Claims17
A controlled growth apparatus, comprising:
- a chamber capable of holding a substrate onto which a film is grown;
- a plurality of sources within said chamber capable of simultaneously irradiating a surface of said substrate with a plurality of respective growth species to form said film;
- at least one metering device capable of controlling an amount of a respective one of said species irradiated upon said surface;
- an ellipsometer operable during an operation of said sources, illuminating said surface with a beam of light, and providing a time-ordered sequence of a plurality of ellipsometric data from light reflected by said surface from said beam of light;
- and
- a controller generating a control signal from said time-ordered sequence of said plurality of said ellipsometric data, said control signal independently controlling each of said at least one metering device during said operation of said sources.
A method of controllably growing a film, comprising the steps of:
- simultaneously irradiating a surface with a plurality of growth species, whereby a film is grown on said surface;
- illuminating said surface with an incident beam of light during said irradiating step, whereby light is reflected from said surface in a reflected beam of light;
- deriving ellipsometric data from said incident and reflected beams;
- and
- dynamically controlling said irradiating step in response to said ellipsometric data, wherein said controlling step controls relative rates at which said irradiating step irradiates said surface with said plurality of species.
For use with a growth apparatus including a plurality of sources simultaneously irradiating a surface with different growth species to form a multi-element film thereon and at least one metering device controlling a relative amount of the different species irradiated by the associated source, an ellipsometric growth control apparatus comprising:
- an ellipsometer operable during an operation of said sources, illuminating said surface with a beam of light, and providing complementary ellipsometric data from light reflected by said surface from said beam of light, said complementary ellipsometric data characterizing a polarization state of said reflected light;
- and
- a controller receiving data from said ellipsometer during said operation of said sources and generating a control signal from a time-ordered sequence of said ellipsometric data for controlling said relative amount of said growth species irradiated by said sources.
Dependencies are inferred from the claim text.