Processing a workpiece using water, a base, and ozone

• US 7,163,588 B2
• Filed: 12/06/2004
• Issued: 01/16/2007
• Est. Priority Date: 05/09/1997
• Status: Expired due to Fees

• Current Assignee: OEM Group, LLC
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: Bergman, Eric J.
• Primary Examiner(s): El-Arini; Zeinab
• Application Number:
  US11/005,495
• Publication Number:
  US 20050133067A1
• Time in Patent Office: 771 Days
• Field of Search: 134/2, 134/18, 134/19, 134/25.4, 134/26, 134/29, 134/30, 134/33, 134/902
• US Class Current: 134/2
• CPC Class Codes: B08B 2203/005 the liquid being ozonated
• CPC Class Codes: B08B 2203/007 Heating the liquid
• CPC Class Codes: B08B 2230/01 Cleaning with steam
• CPC Class Codes: B08B 3/00 Cleaning by methods involving the use or presence of liquid or steam B08B9/00 takes precedence
• CPC Class Codes: B08B 3/02 Cleaning by the force of jets or sprays
• CPC Class Codes: B08B 3/044 using agitated containers in which the liquid and articles or material are placed by means of ultrasonic vibrations B08B3/12; cleaning casks or barrels by agitating B08B9/0817; mixers with shaking, oscillating or vibrating mechanisms B01F31/00
• CPC Class Codes: B08B 3/08 the liquid having chemical or dissolving effect substances used, see the relevant classes
• CPC Class Codes: B08B 7/00 Cleaning by methods not provided for in a single other subclass or a single group in this subclass
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/02054 combining dry and wet cleaning steps H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/6704 for wet cleaning or washing
• CPC Class Codes: H01L 21/67051 using mainly spraying means, e.g. nozzles
• CPC Class Codes: Y10S 134/902 Semiconductor wafer

Abstract

Contaminants such as photoresist are quickly removed from a wafer having metal features, using water, ozone and a base such as ammonium hydroxide. Processing is performed at room temperature to avoid metal corrosion. Ozone is delivered into a stream of process liquid or into the process environment or chamber. Steam may alternatively be used. A layer of liquid or vapor forms on the wafer surface. The ozone moves through the liquid layer via diffusion, entrainment, jetting/spraying or bulk transfer, and chemically reacts with the photoresist, to remove it.

Claims

1. A method for cleaning at least one workpiece, comprising:

placing the workpiece into a chamber;

spraying a liquid onto the workpiece, with the liquid including water and ammonium hydroxide, and with the liquid forming a liquid layer on the workpiece;

controlling the thickness of the liquid layer by one or more of rotating the workpiece, adding a surfactant, or controlling the flow rate of the liquid; and

providing ozone in the chamber, with at least some of the ozone diffusing through the liquid layer and chemically reacting with a contaminant on the workpiece, to clean the workpiece.

2. The method of claim 1 with the liquid having a concentration of water to ammonium hydroxide ranging from about 1500:

1 to 3000;

1.

3. The method of claim 1 further comprising heating one or more of the liquid, the workpiece, and the chamber.

4. The method of claim 1 with the liquid layer having a thickness of about 1–

100 microns.

5. The method of claim 1 with liquid at about ambient temperature.

6. A method for removing photoresist from a surface of a workpiece, comprising:

placing the workpiece into a chamber;

closing the chamber, and providing ozone gas into the chamber;

spraying a liquid at a controlled rate onto a surface of the workpiece having a coating of photoresist, with the liquid including water and a base;

forming the liquid into a layer on the workpiece;

controlling the thickness of the liquid layer; and

providing ozone to the liquid layer, with the ozone oxidizing the photoresist in the presence of the liquid, and removing the photoresist.

7. The method of claim 6 further comprising heating the liquid to about 30–

100°

C.

8. The method of claim 6 where the photoresist is a negative photoresist.

9. The method of claim 6 wherein the workpiece has one or more metal features, and with the liquid at about 15–

29°

C. to avoid substantial corrosion of the metal features.

10. The method of claim 6 where the base comprises tetra-methyl ammonium hydroxide, KOH or NaOH.

11. The method of claim 6 where the liquid comprises water and the base comprises ammonium hydroxide and where the ratio of water to ammonium hydroxide ranges from about 1000:

1 to about 5000;

1.

12. The method of claim 6 wherein the workpiece has a NiCr film.

13. The method of claim 6 wherein the ozone gas is provided into the chamber separately from the liquid.

14. A method for reducing corrosion of metal features on a wafer during cleaning of the wafer, comprising:

placing the workpiece into a chamber;

spinning the wafer;

contacting the spinning wafer with a liquid including water and ammonium hydroxide, with the liquid forming into a liquid layer on the wafer;

controlling the thickness of the liquid layer;

providing ozone into the liquid layer, with the ozone oxidizing a contaminant on the wafer; and

with the ammonium hydroxide acting to reduce corrosion of the metal features, in the presence of water and ozone.

15. The method of claim 14 further including heating the liquid to 30–

100°

C.

16. The method of claim 14 with the concentration of ammonium hydroxide in the liquid ranging from about 1:

20 to about 1;

250.

17. The method of claim 14 wherein at least one of the metal features comprises NiCr.

18. The method of claim 14 wherein at least one of the metal features comprises silver.

19. The method of claim 14 wherein the wafer includes one or more MEMS devices.