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Apparatus and method for detecting particles in reactive and toxic gases

Imported: 23 Feb '17 | Published: 22 Oct '02

Wayne Thomas McDermott, Richard Carl Ockovic

USPTO - Utility Patents

Abstract

An apparatus and a method are disclosed for detecting particles in a particle-containing gas at a pressure greater than about 0 psig. The apparatus includes a gas distribution line containing a pressurized gas having a pressure greater than about 0 psig and a condensation nucleus counter in fluid communication with the pressurized gas in the gas distribution line. The condensation nucleus counter is adapted to receive a stream of the pressurized gas at a pressure substantially equal to the pressure of the pressurized gas in the gas distribution line. The condensation nucleus counter is constructed of materials resistant to corrosion and to reaction with the pressurized gas, which may be one or more reactive or toxic gases, such as those used in microchip processing, or an inert gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a condensation nucleus counter according to the present invention;

FIG. 2 is a cross-sectional side view taken along lines 2—2 of the condensation nucleus counter shown in FIG. 1 with the addition of thermal insulation and a photo detector;

FIG. 3A is a graph illustrating the counting efficiency of the condensation nucleus counter according to the present invention for seven different gases; and

FIG. 3B is a graph illustrating the counting efficiency of the condensation nucleus counter according to the present invention for six other gases.

Claims

1. An apparatus for detecting particles in a particle-containing gas at a pressure greater than about 0 psig, comprising:

2. An apparatus as in claim 1, wherein the pressurized gas is selected from the group consisting of SiCl

4, PH

3, B

2H

6, AsH

3, SiF

4, Si

2H

6, NH

3, BCl

3, BF

3, Cl

2, H

2, HBr, HCl, HF, NF

3, N

2O, O

2, SiH

4, WF

6, N

2, Ar, He, CF

4, CHF

3, C

2F

6, and SF

6, and mixtures thereof.

3. An apparatus as in claim 1 further comprising a means for determining the number of at least one particle in the pressurized gas.

4. An apparatus as in claim 3 further comprising a means for tabulating the number of the at least one particle.

5. An apparatus as in claim 4, wherein the means for tabulating is a computer.

6. An apparatus as in claim 1, wherein the condensation nucleus counter comprises:

7. An apparatus as in claim 1, wherein the condensation nucleus counter is constructed of materials resistant to corrosion and to reaction with the pressurized gas selected from the group consisting of SiCl

4, PH

3, B

2H

6, AsH

3, SiF

4, Si

2H

6,NH

3, BCl

3, BF

3, Cl

2, H

2, HBr, HCl, HF, NF

3, N

2O, O

2, SiH

4, WF

6, N

2, Ar, He, CF

4, CHF

3, C

2F

6, and SF

6, and mixtures thereof.

8. A gas distribution system containing a pressurized gas having a pressure greater than about 0 psig, the improvement comprising:

9. A method of detecting particles in a particle-containing gas at a pressure greater than about 0 psig, comprising the steps of:

10. A method as in claim 9, further comprising the step of determining the number of at least one particle in the pressurized gas - introduced into the condensation nucleus counter.

11. A method as in claim 9, wherein the pressurized gas is selected from the group consisting of SiCl

4, PH

3, B

2H

6, AsH

3, SiF

4, Si

2H

6, NH

3, BCl

3, BF

3, Cl

2, H

2, HBr, HCl, HF, NF

3, N

2O, O

2, SiH

4, WF

6, N

2, Ar, He, CF

4, CHF

3, C

2F

6, and SF

6 and mixtures thereof.

12. A method as in claim 10, further comprising the step of tabulating the number of the at least one particle.

13. A method as in claim 12, wherein a computer is used for tabulating.

14. A method as in claim 9, wherein the particles are detected at an at least approximately 50% counting efficiency.

15. A method as in claim 9, wherein the pressure is about 60 psig.

16. A method as in claim 10, wherein the step of determining the number of at least one particle in the pressurized gas comprises the sub-steps of:

17. A method as in claim 16, wherein the working fluid is perfluorotrimethylcyclohexane.

18. A method as in claim 16, wherein the working fluid is a non-reactive fluid.

19. A method as in claim 18, wherein the non-reactive working fluid is Multifluor® fluid.