In-situ local heating using megasonic transducer resonator

• US 20030183246A1
• Filed: 03/29/2002
• Published: 10/02/2003
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Boyd, John M., Mikhaylich, Katrina
• Granted Patent: US 6,845,778 B2
• Time in Patent Office: Days
• US Class Current: 134/1.3
• CPC Class Codes: B08B 17/02 Preventing deposition of fouling or of dust
• CPC Class Codes: B08B 2203/0288 Ultra or megasonic jets
• CPC Class Codes: B08B 3/02 Cleaning by the force of jets or sprays
• CPC Class Codes: B08B 3/10 with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
• CPC Class Codes: B08B 3/12 by sonic or ultrasonic vibrations washing or rinsing machines for crockery or tableware using sonic or ultrasonic waves A47L15/13; of natural teeth, of prostheses using ultrasonic techniques similar to those used for natural teeth A61C17/20; application of ultrasonic vibrations to chemical, physical or physico-chemical processes in general B01J19/10
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/67051 using mainly spraying means, e.g. nozzles
• CPC Class Codes: Y10S 134/902 Semiconductor wafer

Abstract

An apparatus for cleaning a semiconductor substrate is provided. In embodiment of the present invention, a megasonic cleaner capable of providing localized heating is provided. The megasonic cleaner includes a transducer and a resonator. The resonator is configured to propagate energy from the transducer. The resonator has a first and a second end, the first end is operatively coupled to the transducer and the second end is configured to provide localized heating while propagating the energy from the transducer. A system for cleaning a semiconductor substrate through megasonic cleaning and a method for cleaning a semiconductor substrate is also provided.

Claims

1. An apparatus for cleaning a semiconductor substrate, the apparatus comprising:

a transducer;

a resonator configured to propagate energy from the transducer, the resonator having a top surface and a bottom surface, the top surface operatively coupled to the transducer, the bottom surface configured to provide localized heating while propagating the energy from the transducer.

2. The apparatus of claim 1, further including:

an insulator positioned between the transducer and the resonator.

3. The apparatus of claim 1, wherein the resonator is composed of a Silicon carbide layer having a thickness between about 0.01 millimeter (mm) and about 7 mm.

4. The apparatus of claim 1, wherein the bottom surface is a curved surface.

5. The apparatus of claim 4, wherein the curved surface has a radius of curvature between about 5 centimeters (cm.) and 200 cm.

6. The apparatus of claim 1, further including:

a cooling loop for cooling the transducer, the cooling loop being a closed loop.

7. A system for cleaning a semiconductor substrate, the system comprising:

a substrate support configured to support and rotate a semiconductor substrate about an axis of the semiconductor substrate;

a megasonic cleaner configured to move radially above a top surface of the semiconductor substrate, the mega sonic cleaner including;

a transducer;

a resonator configured to propagate energy from the transducer, the resonator having a top surface and a bottom surface, the top surface is operatively coupled to the transducer, the bottom surface is configured to contact a liquid disposed on the top surface of the semiconductor substrate, the bottom surface adapted to provide localized heating to elevate a temperature of the liquid in contact with the bottom surface while propagating the energy from the transducer through the liquid to the substrate.

8. The system of claim 7, wherein the bottom surface is configured to direct megasonic waves at an angle toward the top surface of the semiconductor substrate.

9. The system of claim 7, wherein a distance from the top surface of the semiconductor substrate to the bottom surface of the resonator is between about 0.5 millimeter and about 5 millimeters.

10. The system of claim 7, wherein the liquid is one of a cleaning chemistry designed for single wafer cleaning operations and deionized water.

11. The system of claim 7, wherein a temperature of the liquid is maintained between about 20 degrees Celsius (C.) and about 100 degrees C. through the localized heating.

12. The system of claim 7, wherein the bottom surface includes a dopant, the dopant configured to reduce a resistivity of the bottom surface.

13. The system of claim 12, wherein the dopant is one of boron, arsenic, phosphorous and antimony.

14. The system of claim 12, wherein a concentration of the dopant is between about 10¹¹ atoms per square centimeter and about 10¹⁹ atoms per square centimeter.

15. The system of claim 7, wherein a voltage differential is applied across the bottom surface to heat the liquid.

16. The system of claim 15, wherein the temperature of the liquid is controlled by varying the voltage differential.

17. The system of claim 7, further including:

a process arm for supporting the megasonic cleaner, the process arm controlled such that an amount of work performed by the megasonic cleaner is substantially uniform over the top surface of the semiconductor substrate.

18. The system of claim 15, wherein the transducer includes at least one port for delivering the liquid to the substrate.

19. A method for cleaning a semiconductor substrate, the method comprising:

introducing a liquid onto a top surface of the semiconductor substrate;

coupling a bottom surface of a resonator to the top surface of the semiconductor substrate through the liquid;

transmitting sonic energy through the resonator to the liquid; and

heating the liquid through the bottom surface of the resonator.

20. The method of claim 19, wherein the method operation of heating the liquid through the bottom surface of the resonator further includes:

reducing a resistivity of a bottom layer of the resonator; and

applying a voltage differential across the bottom layer.

21. The method of claim 19, wherein the method operation of coupling a bottom surface of a resonator to the top surface of the semiconductor substrate through the liquid further includes:

positioning the resonator over the top surface of the semiconductor substrate such that a distance between the bottom surface of the resonator and the top surface of the semiconductor substrate is between about 0.5 millimeters (mm) and about 5 mm.

22. The method of claim 19, wherein the method operation of transmitting sonic energy through the resonator to the liquid further includes;

maintaining a level of sonic energy delivered to the top surface of the semiconductor substrate between about 3 Watts (W) per square centimeter and about 5 W per square centimeter.

23. A method for applying localized heating to a cleaning chemistry during a cleaning operation of a semiconductor substrate, the method comprising:

positioning a resonator to contact a surface of a cleaning chemistry applied to a semiconductor substrate; and

simultaneously applying heat energy and sonic energy through the resonator to clean the semiconductor substrate.

24. The method of claim 23, wherein the method operation of simultaneously applying heat energy and sonic energy through the resonator to clean the semiconductor substrate further includes:

reducing a resistivity of a bottom layer of the resonator;

applying a voltage differential across the bottom layer while transmitting sonic energy from the resonator to the semiconductor substrate through the cleaning chemistry.

25. The method of claim 24, wherein the voltage differential determines a temperature of the cleaning chemistry between the bottom layer of the resonator and top surface of the semiconductor substrate.

26. The method of claim 24 wherein the method operation of reducing a resistivity of a bottom layer of the resonator further includes:

applying a dopant to the bottom layer of the resonator.