Non-contact measurement of a stress in a film on a substrate
AssigneeApplejack 199 L.P.
InventorsWojciech Jan Walecki, Oanh Nguyen
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Abstract
A method for non-contact measurement of stress in a thin-film deposited on a substrate is disclosed. The method may include measuring first topography data of a substrate having a thin-film deposited thereupon. The method may also include comparing the first topography data with second topography data of the substrate that is measured prior to thin-film deposition. The method may further include obtaining a vertical displacement of the substrate based on the comparison between the first topography data and the second topography data. The method may also include detecting a stress value in the thin-film deposited on the substrate based on a fourth-order polynomial equation and the vertical displacement.
Claims8
An apparatus for non-contact based measurement of stress in a thin-film deposited on a substrate, the apparatus comprising:
- a topography measurement unit comprising:
- at least one LED panel configured to emit a beam of light towards a surface of a substrate;
- and
- at least one camera configured to capture a reflected beam of light that includes at least a portion of the emitted beam as reflected from the surface of the substrate;
- and
- a detector unit configured to detect a change in an optical path of the reflected beam of light to determine topography data of the substrate;
- and
- a processor configured to:
- compare first topography data of the substrate having a thin-film deposited thereupon with second topography data of the substrate that is measured prior to the thin-film deposition;
- obtain a vertical displacement of the substrate based on the comparison between the first topography data and the second topography data;
- determine one or more coefficients of a fourth-order polynomial equation that is used to determine a calculated shape of the substrate for different values of stress in the thin-film deposited on the substrate, wherein the one or more coefficients are determined based on the vertical displacement such that the calculated shape as determined from the fourth-order polynomial is similar to an actual shape of the substrate;
- and
- detect a stress value in the thin-film deposited on the substrate based on the fourth-order polynomial equation with the determined one or more coefficients.
An apparatus for non-contact based measurement of stress
- in a thin-film deposited on a substrate, the apparatus comprising:
- a plurality of LED panels configured to emit an emitted beam of light towards a surface of a substrate;
- the plurality of LED panels being arranged to include an opening at about a center for allowing flow of filtered air above the surface of the substrate;
- a plurality of cameras configured to capture a reflected beam of light that includes at least a portion of the emitted beam as reflected from the surface of the substrate;
- a detector unit to determine topography data of the substrate prior to a thin-film deposition and after the thin-film deposition on the substrate, wherein the detector unit is configured to detect a change in optical path of the reflected beam of light to determine the topography data of the substrate;
- and
- a processor configured to cause performance of operations comprising:
- compare first topography data of the substrate having a thin-film deposited thereupon with second topography data of the substrate that is measured prior to the thin-film deposition;
- obtain a vertical displacement of the substrate based on the comparison between the first topography data and the second topography data;
- determine one or more coefficients of a fourth-order polynomial equation that is used to determine a calculated shape of the substrate for different values of stress in the thin-film deposited on the substrate, wherein the one or more coefficients are determined based on the vertical displacement such that the calculated shape as determined from the fourth-order polynomial is similar to an actual shape of the substrate;
- and
- detect a stress value in the thin-film deposited on the substrate based on the fourth-order polynomial equation with the determined one or more coefficients.
Dependencies are inferred from the claim text.