Optical transmission/reflection mode in-situ deposition rate control for ice fabrication

Patent metadata

Field	Value
Publication number	US-2016130696-A1
Application number	US-201414432844-A
Country	US
Kind code	A1
Filing date	May 8, 2014
Priority date	May 8, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

Systems and methods of controlling a deposition rate during thin-film fabrication are provided. A system as provided may include a chamber, a material source contained within the chamber, an electrical component to activate the material source, a substrate holder to support the multilayer stack and at least one witness sample. The system may further include a measurement device and a computational unit. The material source provides a layer of material to the multilayer stack and to the witness sample at a deposition rate controlled at least partially by the electrical component and based on a correction value obtained in real-time by the computational unit. In some embodiments, the correction value is based on a measured value provided by the measurement device and a computed value provided by the computational unit according to a model.

First claim

1 . A system for fabricating an optical thin-film device, comprising:
a chamber; a material source contained within the chamber; an electrical component to activate the material source; a substrate holder to support a multilayer stack of materials that form the optical thin-film device and at least one witness sample; a measurement device; and a computational unit, wherein the material source provides a layer of material to the multilayer stack and to the witness sample at a deposition rate controlled at least partially by the electrical component and based on a correction value obtained by the computational unit, and wherein the correction value is based on a measured value provided by the measurement device and a computed value provided by the computational unit according to a model.

2 . The system of claim 1 , wherein the material source includes two materials having a first index of refraction and a second index of refraction, and the multilayer stack comprises at least a first layer formed of the first material and at least a second layer formed of the second material.

3 . The system of claim 1 , wherein the measurement device comprises an optical measurement device including at least one of an ellipsometer, a spectrometer, and an interferometer.

4 . The system of claim 3 , wherein the optical measurement device comprises an optical source configured to generate an electromagnetic radiation and a detector configured to measure an interacted electromagnetic radiation.

5 . The system of claim 3 , wherein the optical measurement device is configured in one of a transmission mode, a reflection mode, and a transmission and reflection mode.

6 . The system of claim 1 , wherein the optical thin-film device is an integrated computational element used for analyzing a substance in real time.

7 . A method for fabricating an optical thin-film device, the method comprising:
depositing a layer of material on a substrate; measuring an optical property of the layer to obtain a deposition rate; determining a pre-selected threshold based on an optical model; decreasing the deposition rate when the deposition rate is higher than the pre-selected threshold; and increasing the deposition rate when the deposition rate is lower than the pre-selected threshold.

8 . The method of claim 7 , wherein measuring the optical property of the layer comprises continuously measuring the optical property as the layer is being deposited.

9 . The method of claim 7 , wherein measuring the optical property of the layer comprises measuring an interacted electromagnetic radiation transmitted through at least a portion of the layer.

10 . The method of claim 7 , wherein measuring the optical property of the layer comprises measuring an interacted electromagnetic radiation reflected from at least a portion of the layer.

11 . The method of claim 7 , wherein decreasing the deposition rate comprises determining that an optical thickness of the layer of material is less than a desired optical thickness.

12 . The method of claim 7 , wherein decreasing the deposition rate comprises determining that a material density of the layer of material is lower than a desired material density.

13 . The method of claim 7 , wherein increasing the deposition rate comprises determining that a material density of the layer of material is higher than a desired material density.

14 . The method of claim 7 , wherein the pre-selected threshold is based on a stoichiometry of the layer of material.

15 . The method of claim 7 , wherein the pre-selected threshold is based on a desired index of refraction of the layer of material.

16 . The method of claim 7 , wherein measuring an optical property comprises performing at least one of an ellipsometer measurement, a spectrometer measurement, an interferometer measurement, and a continuous multi-wavelength measurement.

17 . The method of claim 7 , wherein determining the pre-selected threshold comprises performing a PID loop including the optical model, the measured deposition rate, and at least a previously measured deposition rate.

18 . A method of forming an optical thin-film device, comprising:
depositing a layer of material on a substrate; measuring an optical property of the layer to obtain a deposition rate; selecting a threshold to achieve consistent optical properties for a plurality of layers of a similar material in the optical thin-film device; decreasing the deposition rate when the optical property is lower than the threshold; and increasing the deposition rate when the optical property is higher than the threshold.

19 . The method of claim 18 , wherein measuring the optical property of the layer comprises continuously measuring the optical property as the layer is being deposited.

20 . The method of claim 18 , wherein the threshold is a desired material density of the layer of material.

21 . The method of claim 18 , wherein measuring the optical property comprises measuring an optical density.

22 . The method of claim 18 , wherein the threshold is based on a desired stoichiometry of the layer of material.

23 . The method of claim 18 , wherein the threshold is based on a desired optical thickness of the layer of material.

Assignees

• Halliburton Energy Services Inc

Inventors

• Price James M
• Nayak Aditya B
• Perkins David L

Classifications

• C23C14/22 Primary

  characterised by the process of coating · CPC title

• C23C14/30

  by electron bombardment · CPC title

• G02B5/285

  comprising deposited thin solid films (G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361) · CPC title

• C23C14/54 Primary

  Controlling or regulating the coating process · CPC title

• G01N21/41

  Refractivity; Phase-affecting properties, e.g. optical path length (G01N21/21 takes precedence) · CPC title