Combined use of oscillating means and ellipsometry to determine uncorrelated effective thickness and optical constants of accumulated material
AssigneeJ.A. Woollam Co., Inc.
InventorsJohn A. Woollam, James D. Welch
Life of this patent
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Abstract
A combined ellipsometer and oscillator system and method of decorrelated determination of thickness and optical constants of deposted materials. In use the ellipsometer determines the product of thickness and optical constant, and the oscillator system changes frequency of oscillation proportional to the thickness of material deposited upon a surface of an element therein.
Claims9
A method of determining an effective thickness of a material caused to accumulate on a surface, in uncorrelated combination with determination of optical constants of said material, comprising the steps of:
- a) providing an oscillating means having a surface area, said oscillating means being a part of an oscillator circuit such that it is caused to physically vibrate or support resonant or non-resonant acoustic waves when electrical potential is applied thereto;
- b) simultaneously or sequentially:
- b1) causing material to accumulate onto the surface of said oscillating means before and/or while it is caused to vibrate and/or support resonant or non-resonant acoustic waves at a frequency;
- and
- b2) causing a beam of electromagnetic radiation to interact with said surface area of said oscillating means and then enter a data detector;
- c) in functional conjunction with step b) determining a relationship between a change in frequency of said oscillating means vs. effective thickness material accumulated thereupon, and providing a mathematical model of the oscillating means and accumulated material system which includes said effective thickness, and optical constants of the accumulated material;
- d) analyzing change in frequency of said oscillating means to determine effective thickness of said accumulated material, and performing regression of the data detector provided data onto said mathematical model to determine optical constants of said accumulated material in view of said determined effective thickness.
A method of determining uncorrelated thickness and optical constants of a deposited material comprising determining an effective thickness of a material in uncorrelated combination with optical constants of said material, comprising the steps of:
- a) providing a sample having a surface area, and an oscillating means having a separate surface area, said oscillating means being a part of an oscillator circuit such that it is caused to physically vibrate or support resonant or non-resonant acoustic waves when electrical potential is applied thereto;
- b) causing material to simultaneously acumulate on said surface of said sample and said surface of said oscillating means;
- c) simultaneously causing:
- c1) material to accumulate onto the surface of said oscillating means before and/or while it is caused to vibrate or support resonant or non-resonant acoustic waves at a frequency;
- and
- c2) material to accumulate onto the surface of said sample before and/or while a beam of electromagnetic radiation to interact with said surface area of said sample and then enter a data detector;
- said material accumulated on both surfaces being substantially similar;
- d) in functional conjunction with step c) determining a relationship between a change in frequency of said oscillating means vs. effective thickness of material accumulated thereupon, and providing a mathematical model of the sample and accumulated material system which includes effective thickness and optical constants of the accumulated material;
- e) analyzing change in frequency of said oscillating means to determine effective thickness of said accumulated material, and performing regression of the data detector provided data onto said mathematical model to determine optical constants of said accumulated material in view of said determined effective thickness.
A method of determining density of material deposited onto a surface of an oscillating means comprising the steps of:
- a) depositing material of known refractive index onto a surface of an oscillating means of known surface area, and detecting a change in the frequency of oscillation;
- b) by application of an ellipsometer or polarimeter determining the product of the refractive index and thickness of said deposited material;
- c) dividing the product of the refractive index and thickness of said deposited material determined in step b, by the known refractive index of said material to determine an effective thickness;
- d) utilizing the known surface area of the oscillating means onto which said material is deposited, and the thickness of said material determined in step c, and the change in frequency of the oscillating means detected in step a which is proportional to the mass of the deposited material, determining the mass per unit volume.
Dependencies are inferred from the claim text.