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US 5,847,283 AGranted
Method and apparatus for the evaluation of a depth profile of thermo-mechanical properties of layered and graded materials and coatings
AssigneeMassachusetts Institute of Technology
InventorsMarc Finot, Olivera Kesler, Subra Suresh
Life of this patent
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Abstract
A technique for determining properties such as Young's modulus, coefficient of thermal expansion, and residual stress of individual layers within a multi-layered sample is presented. The technique involves preparation of a series of samples, each including one additional layer relative to the preceding sample. By comparison of each sample to a preceding sample, properties of the topmost layer can be determined, and residual stress at any depth in each sample, resulting from deposition of the top layer, can be determined.
Claims40
A method comprising:
- providing a first multi-layered sample including at least a first film of a first material in a first thickness and a second film of a second material in a second thickness on the first film, the second film having a first side adjacent the first film and an opposing, second side having not had additional material applied thereto;
- providing a second multi-layered sample including at least a first film of the first material in the first thickness, a second film of the second material in the second thickness on the first film, and a third film of a third material in a third thickness on the second film, the third film having a first side adjacent the second film and an opposing, second side having not had additional material applied thereto;
- providing values of stiffness, neutral axis position, and average Young's modulus of the first sample;
- determining thickness of the third film;
- measuring the stiffness of the second sample;
- and
- determining Young's modulus of the third film from the stiffness measurement of the second sample, the values of stiffness, neutral axis position, and average Young's modulus of the first sample, and thickness of the third film.
4 more elements
A method comprising:
- providing a first sample of a first film of a first material in a first thickness, having a surface;
- applying a bending force to the first sample while directing electromagnetic radiation at the surface and measuring an angle of deflection of the electromagnetic radiation from the surface, thereby determining curvature of the first sample due to the applied bending force;
- providing a second sample including a first film of the first material in the first thickness and a second film of a second material in a second thickness on the first film, having a surface;
- applying a bending force to the second sample while directing electromagnetic radiation at the surface of the second sample and measuring an angle of deflection of the electromagnetic radiation from the surface, thereby determining curvature of the second sample due to the applied bending force;
- determining stiffness of each of the first and second samples from the curvature of each sample due to bending force;
- determining thickness of the second film;
- providing values of neutral axis position and average Young's modulus of the first sample;
- and
- determining Young's modulus of the second film from the stiffness measurements of the first and second samples, the neutral axis position and average Young's modulus of the first sample, and thickness of the second film.
6 more elements
A method comprising:
- providing a first sample created by depositing a first film of a first material in a first thickness on a substrate, the first material differing in composition from the substrate, the sample having a surface;
- applying a bending force to the sample while directing electromagnetic radiation at the surface and measuring an angle of deflection of the electromagnetic radiation from the surface, thereby determining curvature of the sample due to the applied bending force;
- providing values of stiffness, neutral axis position, and average Young's modulus of the substrate, determining stiffness of the first sample from the curvature of the sample due to bending force, determining thickness of the first film, and determining Young's modulus of the first film from the stiffness determination of the sample, the neutral axis position and average Young's modulus of substrate, and thickness of the first film.
A method comprising:
- providing values of stiffness, neutral axis position, and average Young's modulus of a first multi-layered sample including at least a first film of a first material in a first thickness and a second film of a second material in a second thickness on the first film, the second film having a first side adjacent the first film and an opposing, second side having not had additional material applied thereto;
- providing a stiffness value of a second multi-layered sample including at least a first film of the first material in the first thickness, a second film of the second material in the second thickness on the first film, and a third film of a third material in a third thickness on the second film, the third film having a first side adjacent the second film and an opposing, second side having not had additional material applied thereto;
- providing a value of thickness of the third film;
- and
- determining Young's modulus of the third film from the stiffness measurement of the second sample, the values of stiffness, neutral axis position, and average Young's modulus of the first sample, and thickness of the third film.
2 more elements
A method comprising:
- providing a first sample including at least a first film of a first material in a first thickness, the first film having a first side and an opposing, second side having not had additional material applied thereto;
- providing a second, multi-layered sample including at least a first film of the first material in the first thickness and a second film of a second material in a second thickness on the first film, the second film having a first side adjacent the first film and an opposing, second side having not had additional material applied thereto;
- providing values of thickness and Poisson ratio of the first sample;
- providing values of stiffness, neutral axis position, and average Young's modulus of the second sample;
- providing a value of Young's modulus of the second film;
- and
- measuring a curvature variation value of the second sample relative to the first sample while a uniform temperature distribution value exists in the second sample and determining residual stress of the second film.
4 more elements
A method comprising:
- providing a first sample including at least a first film of a first material in a first thickness, the first film having a first side and an opposing, second side having not had additional material applied thereto;
- providing a second, multi-layered sample including at least a first film of the first material in the first thickness and a second film of a second material in a second thickness on the first film, the second film having a first side adjacent the first film and an opposing, second side having not had additional material applied thereto;
- providing values of thickness, Poisson ratio, and average coefficient of thermal expansion of the first sample;
- providing values of stiffness, neutral axis position, and average Young's modulus of the second sample;
- providing a value of Young's modulus of the second film;
- measuring a curvature value of each of the first and second samples at at least two different temperatures to obtain a value of curvature variation between the first and second samples as a function of temperature;
- and
- determining coefficient of thermal expansion of the second film.
5 more elements
Dependencies are inferred from the claim text.