Ultrasonic assisted etch using corrosive liquids

• US 7,377,991 B2
• Filed: 06/27/2006
• Issued: 05/27/2008
• Est. Priority Date: 07/24/2003
• Status: Expired due to Term

• Current Assignee: Quantum Global Technologies LLC (Ultra Clean Holdings Incorporated)
• Original Assignee: Applied Materials Incorporated
• Inventors: Chen, Ning, Tan, Samantha
• Primary Examiner(s): Vinh; Lan
• Application Number:
  US11/477,191
• Publication Number:
  US 20060243390A1
• Time in Patent Office: 700 Days
• Field of Search: 438/745, 438/750, 156/345.11, 156/345.18
• US Class Current: 156/345.1
• 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 3/102 with means for agitating the liquid by agitating the container B08B3/042, B08B3/044, B08B3/045, B08B3/06
• CPC Class Codes: C23F 1/44 Compositions for etching metallic material from a metallic material substrate of different composition
• CPC Class Codes: C23G 1/02 with acid solutions
• CPC Class Codes: C23G 3/00 Apparatus for cleaning or pickling metallic material with organic solvents C23G5/04
• CPC Class Codes: H01L 21/67057 with the semiconductor substrates being dipped in baths or vessels

Abstract

An ultrasonic etching apparatus for chemically-etching a workpiece is disclosed. The apparatus includes an outer tank at least partially filled with an aqueous solution, an inner tank at least partially disposed within the outer tank and in contact with aqueous solution, the inner tank at least partially filled with an etching solution, a lid engaged with the mouth of said inner tank; and an ultrasonic transducer coupled to the outer tank to impart ultrasonic energy to the etching solution in said inner tank. Also disclosed are methods of using the apparatus to etch workpieces.

Claims

1. An ultrasonic etching apparatus for chemically-etching a workpiece, the apparatus comprising:

an outer tank adapted to be at least partially filled with an aqueous solution;

an inner tank comprising a chemically-resistant polymer and at least partially disposed within the outer tank and adapted to be in contact with the aqueous solution, the inner tank adapted to be at least partially filled with an etching solution, the inner tank having at least a sidewall and a base and defining an upper mouth, and being receptive to the workpiece;

a lid adapted to be engaged with the upper mouth of the inner tank, wherein a weight of the lid is adapted to create at least a partial seal between the upper mouth of the inner tank and a lower surface of the lid to increase a partial pressure of at least one gas above the etching solution;

an ultrasonic transducer coupled to the outer tank to impart ultrasonic energy to the etching solution in the inner tank; and

a mechanism adapted to impart relative motion between the workpiece disposed in the inner tank and the ultrasonic transducer;

wherein the mechanism comprises a rotary motion actuator for rotating at least one of the inner tank and the ultrasonic transducer.

2. The apparatus of claim 1 further comprising a heating element adapted to regulate a temperature of the aqueous solution.

3. The apparatus of claim 1 further comprising an ultrasonic buffer adapted to be positioned within the aqueous solution and to dampen and/or diffuse the sonic energy imparted to the etching solution.

4. The apparatus of claim 1 further comprising a probe adapted to be positioned within the etching solution and to monitor one or more of the ultrasonic energy, temperature, temperature variations and impurity concentration.

5. The apparatus of claim 1 wherein the inner tank is at least partially filled with the etching solution and the etching solution is essentially static.

6. The apparatus of claim 1 wherein the outer tank is at least partially filled with the aqueous solution and a temperature of the aqueous solution is maintained from about 20°

C. to about 50°

C.

7. An ultrasonic etching apparatus for chemically-etching a workpiece, the apparatus comprising:

an outer tank adapted to be at least partially filled with an aqueous solution;

an inner tank comprising a chemically-resistant polymer and at least partially disposed within the outer tank and adapted to be in contact with the aqueous solution, the inner tank adapted to be at least partially filled with an etching solution, the inner tank having at least a sidewall and a base and defining an upper mouth, and being receptive to the workpiece;

a lid adapted to be engaged with the upper mouth of the inner tank, wherein a weight of the lid is adapted to create at least a partial seal between the upper mouth of the inner tank and a lower surface of the lid to increase a partial pressure of at least one gas above the etching solution to maintain a substantially stable concentration of the etching solution;

wherein the weight of the lid is selected so that the lid releases at least a portion of the at least one gas before a dangerous pressure level of the at least one gas is present within the inner tank;

an ultrasonic transducer coupled to the outer tank to impart ultrasonic energy to the etching solution in the inner tank; and

a mechanism adapted to impart relative motion between the workpiece disposed in the inner tank and the ultrasonic transducer;

wherein the mechanism comprises a rotary motion actuator for rotating at least one of the inner tank and the ultrasonic transducer.

8. The apparatus of claim 7 wherein the inner tank and any portion of the rotational mechanism that may come into contact with the etching solution comprises a material selected from the group consisting of a fluorine resin and high density polyethylene.

9. The apparatus of claim 8 wherein the inner tank generates less than 10 ppb of leachable metal contaminants and 10 ppm of leachable anionic and organic contaminants.

10. An ultrasonic etching apparatus for chemically-etching a workpiece, the apparatus comprising:

an outer tank adapted to be at least partially filled with an aqueous solution;

an inner tank comprising a chemically-resistant polymer and at least partially disposed within the outer tank and adapted to be in contact with the aqueous solution, the inner tank adapted to be at least partially filled with an etching solution, the inner tank having at least a sidewall and a base and defining an upper mouth, and being receptive to the workpiece;

a lid adapted to be engaged with the upper mouth of the inner tank, wherein a weight of the lid is adapted to create at least a partial seal between the upper mouth of the inner tank and a lower surface of the lid to increase a partial pressure of at least one gas above the etching solution to maintain a substantially stable concentration of the etching solution;

wherein the weight of the lid is selected so that the lid releases at least a portion of the at least one gas before a dangerous pressure level of the at least one gas is present within the inner tank; and

an ultrasonic transducer coupled to the outer tank to impart ultrasonic energy to the etching solution in the inner tank wherein the ultrasonic transducer is positioned outside of the aqueous solution and is operably connected to a power oscillator.

11. The apparatus of claim 10 further comprising a heating element adapted to regulate a temperature of the aqueous solution.

12. The apparatus of claim 10 further comprising an ultrasonic buffer adapted to be positioned within the aqueous solution and to dampen and/or diffuse the sonic energy imparted to the etching solution.

13. The apparatus of claim 10 further comprising a probe adapted to be positioned within the etching solution and to monitor one or more of the ultrasonic energy, temperature, temperature variations and impurity concentration.

14. The apparatus of claim 10 wherein the inner tank is at least partially filled with the etching solution and the etching solution is essentially static.

15. The apparatus of claim 10 wherein the outer tank is at least partially filled with the aqueous solution and the temperature of the aqueous solution is maintained from about 20°

C. to about 50°

C.

16. An ultrasonic etching apparatus for chemically-etching a workpiece, the apparatus comprising:

an outer tank adapted to be at least partially filled with an aqueous solution wherein the aqueous solution is a filtered and recirculated deionized water bath;

an inner tank comprising a chemically-resistant polymer and at least partially disposed within the outer tank and adapted to be in contact with the aqueous solution, the inner tank adapted to be at least partially filled with an etching solution, the inner tank having at least a sidewall and a base and defining an upper mouth, and being receptive to the workpiece;

a lid adapted to be engaged with the upper mouth of the inner tank, wherein a weight of the lid is adapted to create at least a partial seal between the upper mouth of the inner tank and a lower surface of the lid to increase a partial pressure of at least one gas above the etching solution to maintain a substantially stable concentration of the etching solution;

wherein the weight of the lid is selected so that the lid releases at least a portion of the at least one gas before a dangerous pressure level of the at least one gas is present within the inner tank; and

an ultrasonic transducer coupled to the outer tank to impart ultrasonic energy to the etching solution in the inner tank.

17. The apparatus of claim 16 further comprising a heating element adapted to regulate a temperature of the aqueous solution.

18. The apparatus of claim 16 further comprising an ultrasonic buffer adapted to be positioned within the aqueous solution and to dampen and/or diffuse the sonic energy imparted to the etching solution.

19. The apparatus of claim 16 further comprising a probe adapted to be positioned within the etching solution and to monitor one or more of the ultrasonic energy, temperature, temperature variations and impurity concentration.

20. The apparatus of claim 16 wherein the inner tank is at least partially filled with the etching solution and the etching solution is essentially static.

21. The apparatus of claim 16 wherein the outer tank is at least partially willed with the aqueous solution and a temperature of the aqueous solution is maintained from about 20°

C. to about 50°

C.

22. The apparatus of claim 16 further comprising a mechanism adapted to impart relative motion between the workpiece disposed in the inner tank and the ultrasonic transducer.

23. The apparatus of claim 22 wherein the mechanism comprises a rod extending through the lid and coupled to the workpiece.

24. The apparatus of claim 22 wherein the mechanism comprises a rotary motion actuator for rotating the substrate about an axis.

25. The apparatus of claim 24, wherein the axis is a substantially horizontal axis.

26. The apparatus of claim 24, wherein the axis is a substantially vertical axis.