Metal fusion bonding – Process – Using high frequency vibratory energy
Patent
1991-09-30
1993-09-14
Ramsey, Kenneth J.
Metal fusion bonding
Process
Using high frequency vibratory energy
228 11, 2281805, B23K 2010, H01L 21607
Patent
active
052441407
ABSTRACT:
An (10) and method is provided for bonding wire (12) to the bond sites (28) of integrated circuits (14). In preferred embodiments gold wire (12) is bonded to aluminum bond pad (28). Apparatus (10) includes a high frequency ultrasonic energy source (20) designed to provide ultrasonic energy at frequencies above about 125 kHz. The ultrasonic energy is imparted to the bonding interface (32) via transducer (18) and capillary (16). The transducer is modified in length and tool clamp point (40) is sited on transducer (18) so that the wavelength of the high frequency ultrasonic energy is at the antinodal point in its application to interface (32) and thus is optimized. In the preferred embodiments of the process the ultrasonic energy is applied at about 350 kHz at ambient temperature. In this fashion, the bond formed between bond end (30) and bond pad (28) is optimized in terms of shear strength, bonding time and processing temperatures.
Particularly beneficial results are noticed with respect to aluminum alloy bond pads such as Al, 2% copper, which were particularly troublesome in terms of intermetallic formation and bond strength in the prior art. Thus according to the invention, the use of high frequency ultrasonic energy in the aforementioned range, superior strength bonds are formed with greater processing parameter flexibility.
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Alfaro Rafael C.
Ramsey Thomas H.
Barndt B. Peter
Brady III W. James
Donaldson Richard L.
Ramsey Kenneth J.
Texas Instruments Incorporated
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