Process and apparatus for removing a contaminant from a substrate

• US 20030175626A1
• Filed: 03/14/2002
• Published: 09/18/2003
• Est. Priority Date: 03/14/2002
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Ryza, Nicholas A., Awtrey, Allan W.
• Granted Patent: US 6,953,654 B2
• Time in Patent Office: Days
• US Class Current: 430/329
• CPC Class Codes: B08B 7/0021 by liquid gases or supercritical fluids
• CPC Class Codes: C23G 5/00 Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: G03F 7/405 Treatment with inorganic or organometallic reagents after imagewise removal
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

Contaminant removal from a substrate can be performed using a supercritical fluid. An apparatus can be configured to operate at conditions that take advantage of higher solubility of a contaminant in its supercritical state compared to its liquid state. The substrate can be exposed to a supercritical fluid in a chamber to remove at least some of the contaminant. Outside the chamber, the supercritical fluid can be cooled to its corresponding liquid state, in which lower solubility of the contaminant may allow the contaminant to separate into a different phase from the liquid phase of the supercritical fluid. Such contaminant removal can be highly advantageous to substrates that withstand only limited amounts of physical or mechanical stress or heat. The contaminant removal can also be used where geometries virtually prevent removal by physical or mechanical means.

Claims

1. A process for removing a contaminant from a substrate comprising:

placing the substrate within a chamber, wherein the substrate includes a pseudoplastic material and the contaminant;

exposing the pseudoplastic material to a supercritical fluid to remove at least part of the contaminant from the substrate; and

removing the substrate from the chamber after exposing,

wherein a shape of the pseudoplastic material, after removing, is not significantly changed when compared to the shape of the pseudoplastic material, before placing.

2. The process of claim 1, wherein the pseudoplastic material comprises a material consisting of resist, polyimide, and spin-on dielectric.

3. The process of claim 1, wherein:

the supercritical fluid comprises molecules with a dipole moment less than approximately one; and

the contaminant includes water.

4. The process of claim 3, wherein the molecules are selected from a group consisting of carbon dioxide and sulfur hexafluoride.

5. The process of claim 4, wherein the supercritical fluid further comprises fluorinated organic molecules.

6. The process of claim 1, further comprising purging the chamber with a gas before exposing, wherein the gas and the supercritical fluid comprise a same molecular compound.

7. The process of claim 1, further comprising separating at least a portion of the contaminant from a compound within the supercritical fluid.

8. The process of claim 7, wherein:

exposing is performed at an exposure temperature of at least a critical temperature of the supercritical fluid; and

separating is performed at a separation temperature below the critical temperature of the supercritical fluid.

9. The process of claim 1, further comprising decompressing the chamber after exposing, wherein decompressing is performed at a rate such that the supercritical fluid does not form a liquid or a solid.

10. The process of claim 1, wherein exposing is performed at a pressure in a range of approximately 1500-3000 psig.

11. The process of claim 1, wherein:

the pseudoplastic material is at least part of a patterned organic layer defining an opening; and

the opening has an aspect ratio of at least approximately 2;

1.

12. The process of claim 1, wherein exposing is performed at least until an endpoint is detected.

13. The process of claim 1, wherein exposing is performed for a set time of at least approximately one minute.

14. A process for removing a contaminant from a substrate comprising:

placing the substrate within a chamber, wherein;

the substrate includes the contaminant; and

the contaminant includes molecules having a dipole moment of at least approximately one;

exposing the substrate to a supercritical fluid to remove at least part of the contaminant from the substrate, wherein the supercritical fluid comprises molecules with a dipole moment less than approximately one; and

removing the substrate from the chamber after exposing.

15. The process of claim 14, wherein the substrate comprises a material consisting of resist, polyimide, and spin-on dielectric.

16. The process of claim 15, wherein:

the resist is at least part of a patterned layer defining an opening;

the opening has an aspect ratio of at least approximately 2;

1; and

at least part of the contaminant lies near a bottom of the opening.

17. The process of claim 16, wherein the supercritical fluid comprises a material selected from a group consisting of carbon dioxide and sulfur hexafluoride.

18. The process of claim 17, wherein the supercritical fluid further comprises fluorinated organic molecules.

19. The process of claim 14, further comprising purging the chamber with a gas before exposing, wherein the gas and the supercritical fluid comprise a same molecular compound.

20. The process of claim 14, further comprising separating at least a portion of the contaminant from a compound within the supercritical fluid.

21. The process of claim 20, wherein:

exposing is performed at an exposure temperature of at least a critical temperature of the supercritical fluid; and

separating is performed at a separation temperature below the critical temperature of the supercritical fluid.

22. The process of claim 14, further comprising decompressing the chamber after exposing, wherein decompressing is performed at a rate such that the supercritical fluid does not form a liquid or a solid.

23. The process of claim 14, wherein exposing is performed at a pressure in a range of approximately 1500-3000 psig.

24. The process of claim 14, wherein exposing is performed at least until an endpoint is detected.

25. The process of claim 14, wherein exposing is performed for a set time of at least approximately one minute.

26. An apparatus for removing a contaminant from a substrate using a supercritical fluid comprising:

a chamber adapted to receive the substrate and configured to withstand a pressure of the supercritical fluid;

a first temperature modulator adapted to cool the supercritical fluid to a liquid; and

a separating portion adapted to aid in separating the contaminant from the liquid, wherein the first temperature modulator lies between the chamber and the separating portion.

27. The apparatus of claim 26, further comprising a second temperature modulator adapted to heat the liquid to the supercritical fluid before reaching the chamber.

28. The apparatus of claim 27, further comprising a controller adapted to control a value of a parameter of the recirculating pump or a value of a parameter of the at least one temperature modulator.

29. The apparatus of claim 27, wherein each of the first and second temperature modulators comprises a heat exchanger.

30. The apparatus of claim 26, wherein the separating portion includes a section lying at an elevation lower than adjacent parts of the apparatus.

31. The apparatus of claim 26, wherein the separating portion lies outside the chamber.

32. The apparatus of claim 26, further comprising a gas feed section including a pressurizing pump that is adapted to increase a pressure of a gas at least to its corresponding supercritical pressure.

33. The apparatus of claim 26, further comprising a recirculating pump and tubing, wherein:

portions of the tubing are connected to the chamber, the first temperature modulator, the separating portion, and the recirculating pump; and

the apparatus includes a portion that is configured to operate as a closed-loop section during at least a point in time, wherein the closed-loop section includes the chamber, the first temperature modulator, the separator portion, the recirculating pump, and the tubing.