In-situ local heating using megasonic transducer resonator

• US 6,845,778 B2
• Filed: 03/29/2002
• Issued: 01/25/2005
• Est. Priority Date: 03/29/2002
• Status: Expired due to Fees

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Boyd, John M., Mikhaylich, Katrina
• Primary Examiner(s): Markoff, Alexander
• Application Number:
  US10/112,639
• Publication Number:
  US 20030183246A1
• Time in Patent Office: 1,033 Days
• Field of Search: 134/902, 134/1, 134/105, 134/184, 134/1.3, 134/19, 134/32, 134/33, 134/34, 134/157
• 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 being doped to reduce a resistivity associated with the bottom surface; and

a process arm supporting the transducer and the resonator over a surface of the semiconductor substrate.

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 megasonic 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 heat the liquid in contact with the bottom surface while propagating the energy from the transducer through the liquid to the substrate, wherein the bottom surface includes a dopant causing a reduction of a resistivity of the bottom surface.

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 bottom surface is a curved surface.

11. The system of claim 7, wherein the bottom surface is a flat surface.

12. The system of claim 7, wherein the dopant is one of boron, arsenic, phosphorous and antimony.

13. The system of claim 7, wherein a concentration of the dopant is between about 10¹¹ atoms per square centimeter and about 10¹⁹ atoms per square centimeter.

14. The system of claim 7, wherein the bottom surface includes wire connections for applying a voltage differential across the bottom surface.

15. The system of claim 14, wherein the bottom surface is in electrical communication with a voltage differential source.

16. The system of claim 7, further including:

a process arm for supporting the megasonic cleaner, the process arm configured to support the megasonic cleaner over the substrate.

17. The system of claim 14, wherein the transducer is contained within a housing, the housing having at least one port for delivering a cooling medium to the transducer.

18. A method for cleaning a semiconductor substrate, the method comprising method operations of:

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;

generating sonic energy;

transmitting the sonic energy through the resonator to the liquid;

applying a voltage differential across the bottom surface to generate heat energy; and

heating the liquid with the heat energy.

19. The method of claim 18, wherein the bottom surface has been doped to reduce a resistivity associated with a bottom layer of the resonator.

20. The method of claim 18, 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.

21. The method of claim 18, 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.

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

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

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

23. The method of claim 22, 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.

24. The method of claim 22 wherein the bottom layer of the resonator has been doped to reduce a resistivity associated with the bottom layer.