Thin film interference filter and bootstrap method for interference filter thin film deposition process control
First Claim
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1. A method for forming a thin film interference filter comprising:
- measuring a reflectance of a stack of a plurality of films;
modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films;
depositing the topmost layer on the stack of the plurality of films; and
recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer;
whereinthe topmost layer is a high index of refraction layer that exhibits a wavelength that is determined according to the characteristics of either the modeled monitor curve or one of the recorded monitor curves; and
determining an anticipated standard deviation in φ
κ
for each different monitor wavelength in the high-index of refraction layer and discarding any monitor wavelengths with σ
greater than 0.9 degrees.
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Abstract
A thin film interference filter system includes a plurality of stacked films having a determined reflectance; a modeled monitor curve; and a topmost layer configured to exhibit a wavelength corresponding to one of the determined reflectance or the modeled monitor curve. The topmost layer is placed on the plurality of stacked films and can be a low-index film such as silica or a high index film such as niobia.
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Citations
27 Claims
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1. A method for forming a thin film interference filter comprising:
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measuring a reflectance of a stack of a plurality of films; modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films; depositing the topmost layer on the stack of the plurality of films; and recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer;
whereinthe topmost layer is a high index of refraction layer that exhibits a wavelength that is determined according to the characteristics of either the modeled monitor curve or one of the recorded monitor curves; and determining an anticipated standard deviation in φ
κ
for each different monitor wavelength in the high-index of refraction layer and discarding any monitor wavelengths with σ
greater than 0.9 degrees. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for forming a thin film interference filter comprising:
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measuring a reflectance of a stack of a plurality of films; modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films; depositing the topmost layer on the stack of the plurality of films; recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer, wherein the topmost layer exhibits a wavelength that is determined according to the characteristics of either the modeled monitor curve or one of the recorded monitor curves; and computing two possible values of phase angle for each monitor wavelength other than the modeled monitor wavelength. - View Dependent Claims (10)
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11. A method for forming a thin film interference filter comprising:
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measuring a reflectance of a stack of a plurality of films; modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films; depositing the topmost layer on the stack of the plurality of films; recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer, wherein the topmost layer exhibits a wavelength that is determined according to the characteristics of either the modeled monitor curve or one of the recorded monitor curves; and using information extracted from the model for rk at each monitor wavelength and the computed best value of δ
, and computing an estimated standard deviation of phase at all monitor wavelengths except the modeled monitor wavelength. - View Dependent Claims (12, 13, 14)
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15. A method for forming a thin film interference filter comprising:
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measuring a reflectance of a stack of a plurality of films; modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films; depositing the topmost layer on the stack of the plurality of films; and recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer, wherein the topmost layer exhibits a wavelength that is determined according to the characteristics of either the modeled monitor curve or one of the recorded monitor curves, the top layer having an intensity of reflectance of greater than 9%; and replacing the magnitude of the amplitude reflectance at each monitor wavelength with √
{square root over (Rk)}. - View Dependent Claims (16, 17, 18)
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19. A method for forming a thin film interference filter comprising:
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measuring a reflectance of a stack of a plurality of films; modeling a monitor curve at a modeled monitor wavelength for a topmost layer to be deposited on the stack of the plurality of films; depositing the topmost layer on the stack of the plurality of films; and recording a plurality of monitor curves during the deposition, each monitor curve being recorded for a different monitor wavelength of the topmost layer; wherein the topmost layer exhibits a reflectance maximum for at least one of the monitor curves being recorded; and obtaining a phase for the reflectance using the measured reflectance and the reflectance maximum, wherein a standard deviation for the phase is found for each of the monitor curves having a reflectance maximum and a reflectance, and a monitor curve is selected such that the standard deviation for the phase is less than a pre-selected value. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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Specification