Method of monitoring a surfactant in a microelectronic process by absorbance
A method of monitoring a surfactant in a microelectronic process is disclosed. Specifically, the monitoring of a surfactant occurs by studying the absorbance of a sample collected from a microelectronic process.
1. A method of monitoring a surfactant in a process for making a microelectronic component comprising:
a. adding the surfactant to a process for making a microelectronic component, wherein an absorbance of the surfactant is capable of being measured, wherein the absorbance is ultraviolet-visible absorbance;
b. sampling fluid from the process;
c. measuring the absorbance of the surfactant in the sample;
d. correlating the absorbance of the surfactant in the sample with the concentration of the surfactant in the process; and
e. taking action to maintain the concentration of the surfactant in the process at a desired level, wherein the desired level is a dilution ratio of about 200 parts total volume to about one part surfactant volume;
wherein the sampling comprises adding a chromogenic agent into the fluid, the chromogenic agent comprising 4,5,6,7-Tetrachloro-2′,4′,5′,7′-tetraiodofluorescein disodium salt.
2. The method of claim 1 wherein the process is a photolithography process.
3. The method of claim 1 wherein the process is a wet-etching process.
4. The method of claim 1 wherein the process is monitored on-line.
5. The method of claim 1 wherein the sampling involves an SIA analysis of the sample or an SFA analysis of the sample.
6. The method of claim 1 wherein sampling uses a LOV module for a sample analysis.
7. The method of claim 1 wherein sampling includes dilution of the sample and/or removal of contaminants from the sample.
8. The method of claim 1 wherein the surfactant is a cationic surfactant.
9. The method of claim 8 wherein the surfactant is a fluorinated surfactant.
10. The method of claim 1 wherein the surfactant is a non-ionic surfactant.
11. The method of claim 10 wherein the surfactant is a fluorinated surfactant.
12. The method on claim 1 wherein the monitoring is continuous, sequential, or at a programmed interval.
13. The method of claim 1 wherein sampling includes measuring an additional process variable, optionally wherein the process variable includes at least one of the following process variables: pH of the process; conductivity of the process stream; and viscosity of the process stream.
14. The method of claim 1 wherein the process is monitored on-line.
15. A method of monitoring a surfactant in a process for making a microelectronic component comprising:
a. adding the surfactant to a process for making a microelectronic component;
b. sampling fluid from the process, the sampling performed subsequent to the addition of the surfactant to the process and also before application of the surfactant to the microelectronic component, the sampling accomplished by drawing the sample into a side stream comprising a flow cell, wherein the sampling includes comprises adding a chromogenic agent to the sample and forming a reacted surfactant;
c. measuring an absorbance of the reacted surfactant in the sample, wherein the absorbance is ultraviolet-visible absorbance;
d. correlating the absorbance of the reacted surfactant with the concentration of the surfactant in the process;
e. taking action to maintain the concentration of the surfactant in the process at a desired level; wherein the desired level is a dilution ratio of about 200 parts total volume to about one part surfactant volume; and
wherein the chromogenic agent is 4,5,6,7-Tetrachloro-2′,4′,5′,7′-tetraiodofluorescein disodium salt.
16. The method of claim 15 further comprising adding at least one modifying agent to the sample, which modifies the absorbance signal of the surfactant positively or negatively.
17. The method of claim 16 wherein said modifying agent positively affects the signal and is a cationic agent selected from the group consisting of: tertiary amines; quaternary amines; tetramethylammonium hydroxide; tetrabutylammonium chloride; cetyltrimethylammonium bromide; and a combination thereof.
18. The method of claim 16 wherein the modifying agent positively affects the signal and is an anionic agent that contains at least one of the following functional groups: sulfonate, carboxylate, and phosphonate.
19. The method of claim 16 wherein said surfactant is a non-ionic surfactant.
20. The method of claim 15 wherein said surfactant is a cationic surfactant.
21. The method of claim 20 wherein the surfactant is a fluorinated surfactant.
22. The method of claim 15 wherein said surfactant is a non-ionic surfactant.
23. The method of claim 22 wherein the surfactant is a fluorinated surfactant.
24. The method of claim 15 wherein the process is a photolithography process.
25. The method of claim 15 wherein the process is a wet-etching process.
26. The method of claim 15 wherein the process is monitored on-line.
27. The method of claim 15 wherein the sampling involves an SIA analysis of the sample or an SFA analysis of the sample.
28. The method of claim 15 wherein sampling uses a LOV module for a sample analysis.
29. The method of claim 15 wherein sampling includes dilution of the sample and/or removal of contaminants from the sample.
30. The method on claim 15 wherein the monitoring is continuous, sequential, or at a programmed interval.
31. The method of claim 15 wherein sampling includes measuring an additional process variable, optionally wherein the process variable includes at least one of the following process variables: pH of the process; conductivity of the process stream; and viscosity of the process stream.