Novel ultrasonic vibration mode for wire bonding

• US 20020096554A1
• Filed: 12/07/2001
• Published: 07/25/2002
• Est. Priority Date: 04/16/1999
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Jiang, Tongbi, Wu, Zhiqiang
• Granted Patent: US 6,685,083 B2
• Time in Patent Office: Days
• US Class Current: 228/180.5
• CPC Class Codes: B23K 20/004 Wire welding
• CPC Class Codes: B23K 2101/38 Conductors
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48724 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/78301 Capillary
• CPC Class Codes: H01L 2224/78347 Piezoelectric transducers
• CPC Class Codes: H01L 2224/78822 Rotational mechanism
• CPC Class Codes: H01L 2224/85045 using a corona discharge, e.g. electronic flame off [EFO]
• CPC Class Codes: H01L 2224/85181 connecting first on the semiconductor or solid-state body, i.e. on-chip, regular stitch
• CPC Class Codes: H01L 2224/85205 Ultrasonic bonding
• CPC Class Codes: H01L 2224/85206 Direction of oscillation
• CPC Class Codes: H01L 24/45 of an individual wire connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/78 : Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/00015 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed as prior art
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15747 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2924/20303 : Ultrasonic frequency [f] 50 Khz=<f< 75 KHz
• CPC Class Codes: H01L 2924/20305 : Ultrasonic frequency [f] 100 Khz=<f< 125 KHz

Abstract

A method and apparatus for creating second order vibrational modes. The apparatus includes a signal generator, a piezoelectric transducer, a plurality of wave propagating beams and reflecting boards. An electric field applied by the signal generator to the piezoelectric transducer induces a unidirectional vibration of the transducer. The vibration is propagated through the beams and reflected by the reflecting boards in a closed polygonal loop. The final reflection direction is perpendicular to the original vibration. A circular or elliptical vibration of the apparatus results. The circular or elliptical vibrational energy can be imparted to the wire bond of an integrated circuit to add strength to the connection.

Claims

1. An ultrasonic transducer device for creating circular or elliptical vibration modes for use in wire bonding, comprising:

a transducer for generating vibrational energy;

a signal generator for applying drive signals to said transducer;

a polygonal ultrasonic wave propagating arm attached to said transducer, said

polygonal arm comprising a plurality of beams and at least one fixed reflection board, said beams and at least one reflection board cooperating to angularly reflect said vibrational energy;

wherein the sum-total of reflected angles is 90°

or any odd multiple thereof.

3. The device of claim 1 or 2 wherein said transducer is a piezoelectric transducer.

4. The device of claim 1 or 2 wherein said arm comprises a triangular shape.

5. The device of claim 1 or 2 wherein said arm is mechanically attached to said transducer.

6. The device of claim 1 or 2 wherein said resultant ultrasonic wave mode is substantially circular.

7. The device of claim 1 or 2 wherein said resultant ultrasonic wave mode is substantially elliptical.

8. The device of claim 1 or 2 wherein said beam(s) total length it governed by:

9. The device of claim 1 or 2 wherein said beam(s) include stainless steel.

10. The device of claim 1 wherein said reflection boards are attached by weld to said beams.

11. The device of claim 5 wherein said reflection boards attach to said beams at a connection point between two beams.

12. The device of claim 1 wherein said reflection boards comprise material with an overall higher Young'"'"'s Modulus than said beams.

14. A method in accordance with claim 13, wherein said second direction is perpendicular to said first direction.

15. A method in accordance with claim 14, wherein the resultant ultrasonic wave mode at said bond site is substantially circular.

16. A method in accordance with claim 14, wherein the resultant ultrasonic wave mode at said bond site is substantially elliptical.

19. The method in accordance with claim 12 further comprising a triangular arm configuration.

20. The method in accordance with claim 12 wherein said ultrasonic vibrational energy is imparted to the bonding site of a wire bonding apparatus.

2. An ultrasonic transducer device for creating circular or elliptical vibration modes for use in wire bonding, comprising:

a transducer for generating vibrational energy;

a signal generator for applying drive signals to said transducer;

an ultrasonic wave propagating arm attached to said transducer, said arm comprising a single beam configured to angularly redirect said vibrational energy;

wherein the sum-total of redirected angles is 90°

or any odd multiple thereof.

13. A method of forming a bond between a wire and a conductive element at a bond site thereon, comprising:

generating ultrasonic energy;

applying a first portion of said ultrasonic energy directly to said bond site in a first direction;

redirecting a second portion of said ultrasonic energy along a medium capable of transmitting said ultrasonic energy; and

applying said second portion of said ultrasonic energy to said bond site in a second direction different from said first direction.

17. A method of creating circular or elliptical ultrasonic vibration modes for use with wire bonding comprising the steps of:

attaching a plurality of beams in a polygonal arm configuration;

attaching said arm to a transducer;

reflecting an ultrasonic vibration generated by said transducer from one beam to the next by a reflecting board; and

arranging the beams such that the angle between the two beams at the attachment point of said arm to said transducer is approximately 90°

or some odd multiple thereof.

18. A method of creating circular or elliptical ultrasonic vibration modes for use with wire bonding comprising the steps of.

attaching a single beam arm in a closed configuration to a transducer;

redirecting an ultrasonic vibration generated by said transducer along the closed path defined by said arm;

arranging said single beam arm such that the angle between the two distal ends of said beam at the attachment point of said arm to said transducer is 90°

or some odd multiple thereof.

21. A polygonal ultrasonic wave propagating arm for attachment to a transducer, said polygonal arm comprising a plurality of beams and at least one fixed reflection board, said beams and at least one reflection board cooperating to angularly reflect vibrational energy.

23. The device of claim 21 or 22, wherein said transducer is a piezoelectric transducer.

24. The device of claim 21 or 22, wherein said beam(s) are configured in a triangular pattern.

25. The device of claim 21 wherein said reflection boards are attached by weld to said beams.

27. The device of claim 21 or 22 wherein said beam(s) total length it governed by:

28. The device of claim 21, wherein the sum-total of reflected angles is approximately 90°

or any odd multiple thereof.

30. The device of claim 21 or 22, wherein said beam(s) comprise stainless steel.

31. The device of claim 21 wherein said reflection boards comprise material with an overall higher density than said beams.

22. An ultrasonic wave propagating arm for attachment to a transducer, said arm comprising a single beam arranged in a closed loop configuration to angularly redirect vibrational energy.

26. The device of claim 25 wherein said reflection boards attach to said beams at a connection point between two beams.

29. The device of claim 22, wherein the angle between the ends of said beam is approximately 90°