Ozone concentration sensor

• US 8,085,401 B2
• Filed: 03/03/2009
• Issued: 12/27/2011
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Levine, Stephan, Seiwert, Johannes, Lohr, Joachim, Brammer, Ulrich, Fittkau, Jens
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Akanbi, Isiaka O
• Application Number:
  US12/397,155
• Publication Number:
  US 20100027017A1
• Time in Patent Office: 1,029 Days
• Field of Search: 356/407, 356409-411, 356432-442, 356445-448
• US Class Current: 356/432
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence

Abstract

An apparatus and method provide measurement of a constituent of a fluid, such as ozone in ozonated water. The apparatus includes a vessel to contain the fluid, a light source configured to direct a first band of light and a second band of light along a substantially shared path though the fluid, and a photosensor that senses the first band of light and the second band of light. The constituent has a greater absorption associated with the first band of light than with the second band of light. The method includes modification of a measured attribute of the component in response to the sensed second band of light to improve the accuracy of the measured attribute.

Claims

1. An apparatus for measuring an attribute of ozone in an ozonated liquid, the apparatus comprising:

a delivery pipeline to carry the ozonated liquid to a process tool, the delivery pipeline including a plurality of reflection sites;

a light source that directs a first band of visible light and a second band of visible light through the ozonated liquid in the delivery pipeline along a substantially shared path defined in part by the plurality of reflection sites, wherein ozone in the ozonated liquid has a greater absorption with the first band of visible light than with the second band of visible light; and

a photosensor that senses the first band of visible light and the second band of visible light passing through the ozonated liquid for measuring an attribute to the ozone in the ozonated liquid, wherein the plurality of reflection sites increase a length of the substantially shared path.

2. The apparatus of claim 1, wherein the delivery pipeline is positioned to permit in situ measurement of the attribute in the ozonated liquid.

3. The apparatus of claim 1, wherein the delivery pipeline is positioned to permit full-flow measurement of the attribute in the ozonated liquid.

4. The apparatus of claim 1, wherein the second band of visible light provides a reference signal to correct measurements derived from the first band of visible light.

5. The apparatus of claim 1, further comprising a second photosensor positioned to sense the first band of visible light and the second band of visible light passed along a portion of the substantially shared path.

6. The apparatus of claim 5, wherein the light source includes a first light-emitting diode to generate the first band of light and a second light-emitting diode to generate the second band of light, the second photosensor facilitating detection and correction of differential aging of the first or second light-emitting diodes.

7. The apparatus of claim 6, wherein the first band of visible light is associated with a yellow-red frequency and a first width, and the second band of visible light is associated with a blue frequency and a second width.

8. The apparatus of claim 6, wherein the first light-emitting diode comprises a yellow-red light-emitting diode to provide the first band of visible light and the second light-emitting diode comprises a blue light-emitting diode to provide the second band of visible light.

9. The apparatus of claim 1, wherein the measurement sensitivity of the apparatus is increased by the increase of the length of the substantially shared path.

10. The apparatus of claim 1, wherein the photosensor is positioned along the substantially shared path for sensing the first and second bands of visible light as the first and second bands of visible light pass through the delivery pipeline.

11. The apparatus of claim 1, further comprising a second photosensor positioned along a longitudinal axis defined by an external surface of the delivery pipeline for sensing the first band of visible light and the second band of visible light passing along the substantially shared path prior to the first and second bands of visible light reaching the photosensor.

12. The apparatus of claim 1, wherein the delivery pipeline comprises a material that defines an inner surface of the delivery pipeline, the material including a plurality of reflection sites to produce a mirror or diffuse reflection of the first or second bands of visible light.

13. The apparatus of claim 1, further comprising a coating on an exterior surface of the delivery pipeline to provide a plurality of reflection sites that produce a mirror or diffuse reflection of the first or second bands of visible light.

14. An ozonated water generator, comprising:

a contactor for introducing ozone gas into water to produce ozonated water;

a delivery pipeline in fluid communication with the contactor for delivery of ozonated water to a process tool, the delivery pipeline including a plurality of reflection sites that define a path;

a light source that directs a first band of visible light and a second band of visible light substantially along the path through the ozonated water in the delivery pipeline, wherein ozone in the ozonated water has a great absorption with the first band of visible light than with the second band of visible light, and wherein the plurality of reflection sites increase a length of the path; and

a photosensor that senses the first band of visible light and the second band of visible light.

15. A method for measuring an attribute of ozone in an ozonated liquid, the method comprising:

selecting a first band of visible light for which ozone has a greater band of absorption than for a second band of visible light;

directing the first and second bands of visible light through a delivery pipeline including a plurality of reflection sites;

sensing the first and second bands of visible light after the first and second bands of visible blight pass along a substantially shared path through the ozonated liquid, the substantially shared path being defined in part by the plurality of reflection sites; and

determining the attribute of the ozone based on the sensed first and second bands of visible light, wherein the plurality of reflection sites increase a length of the substantially shared path.

16. The method of claim 15, further comprising correcting for an intensity loss of the sensed first band of visible light associated with at least one factor other than absorption by ozone in the ozonated liquid.

17. The method of claim 16, wherein the at least one factor comprises at least one of bubbles, a reflectivity of a reflection site of the substantially shared path, an impurity in the ozonated liquid, a mechanical dimension of delivery pipeline containing the ozonated liquid, or any combination thereof.

18. The method of claim 15, further comprising generating the ozonated liquid in an ozonated liquid generation device.

19. The method of claim 18, wherein generating the ozonated liquid comprises introducing ozone gas to the liquid using a contactor.

20. The method of claim 15, further comprising adjusting at least one parameter of an ozonated liquid generation device until the determined attribute of the ozone in the ozonated liquid substantially matches the desired ozone concentration.

21. The method of claim 15, further comprising alternately directing the first band of visible light and the second band of visible light along the substantially shared path, wherein sensing comprises alternately sensing the first band of visible light and the second band of visible light.

22. The method of claim 21, wherein alternately directing further comprises alternately directing no light along the substantially shared path.

23. The method of claim 15 , further comprising sensing at least one of the first band of visible light and the second band of visible light along after the first and second bands of visible light have passed at most a portion of the substantially shared path, and responsively maintaining an emitted intensity of at least one of the first band of visible light and the second band of visible light.

24. An apparatus for measuring an attribute of ozone in an ozonated fluid, the apparatus comprising:

a vessel to contain the ozonated fluid for delivery to a semiconductor process tool;

a light source configured to direct a first band of visible light and a second band of visible light along a substantially shared path though the ozonated fluid in the vessel, the substantially shared path defined in part by a plurality of reflections, wherein the constituent has a greater absorption associated with the first band of visible light than with the second band of visible light; and

a photosensor that senses the first band of visible light and the second band of visible light passing along the substantially shared path, wherein the plurality of reflections increase a length of the substantially shared path.

25. The apparatus of claim 24, wherein the vessel comprises a delivery pipeline for delivering the ozonated fluid to a process tool positioned to permit in situ and near-real-time measurement of the attribute of the ozone in the ozonated fluid.

26. The apparatus of claim 25, wherein the delivery pipeline is positioned to permit full-flow measurement of the attribute of the ozone in the ozonated fluid.