Ming Fung Ng | The University of Hong Kong (original) (raw)
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Hong Kong University of Science and Technology
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Papers by Ming Fung Ng
IEEE Transactions on Advanced Packaging, 2005
The wire bondability of Au/Ni/Cu bond pads with different Au plating schemes, including electroly... more The wire bondability of Au/Ni/Cu bond pads with different Au plating schemes, including electrolytic and immersion plates, are evaluated after plasma treatment. The plasma cleaning conditions, such as cleaning power and time, are optimized based on the process window and wire pull strength measurements for different bond pad temperatures. Difference in the efficiency of plasma treatment in improving the wire bondability for different Au plates is identified. The plasma cleaned bond pads are exposed to air to evaluate the recontamination process and the corresponding degradation of wire pull strength. The changes in bond pad surface characteristics, such as surface free energy and polar functionality, with exposure time are correlated to the wire pull strength, which in turn provides practical information about the shelf life of wire bonding after plasma clenaning.
Applied Physics Letters, 1994
Ballistic-electron emission microscopy (BEEM) has been performed on Au/n-Si(111)7×7 and Au/CaF2/n... more Ballistic-electron emission microscopy (BEEM) has been performed on Au/n-Si(111)7×7 and Au/CaF2/n-Si(111)7×7 in UHV. In both cases, the topography of the Au surface is characterized by ≊2.5 A˚ height terraces, stacked in several stages, with rounded shapes for Au/Si, and hexagonal shapes for Au/CaF2/Si. BEEM up to tip voltages of 8 V on Au/Si is not altering the ballistic transmissivity, in contrast to previous work on Au/Si interfaces which involved chemical preparations of the Si surfaces. The shape of the BEEM spectra on Au/CaF2/Si depends on spectral features of the density of states of the CaF2 thin film.
IEEE Transactions on Advanced Packaging, 2005
The wire bondability of Au/Ni/Cu bond pads with different Au plating schemes, including electroly... more The wire bondability of Au/Ni/Cu bond pads with different Au plating schemes, including electrolytic and immersion plates, are evaluated after plasma treatment. The plasma cleaning conditions, such as cleaning power and time, are optimized based on the process window and wire pull strength measurements for different bond pad temperatures. Difference in the efficiency of plasma treatment in improving the wire bondability for different Au plates is identified. The plasma cleaned bond pads are exposed to air to evaluate the recontamination process and the corresponding degradation of wire pull strength. The changes in bond pad surface characteristics, such as surface free energy and polar functionality, with exposure time are correlated to the wire pull strength, which in turn provides practical information about the shelf life of wire bonding after plasma clenaning.
Applied Physics Letters, 1994
Ballistic-electron emission microscopy (BEEM) has been performed on Au/n-Si(111)7×7 and Au/CaF2/n... more Ballistic-electron emission microscopy (BEEM) has been performed on Au/n-Si(111)7×7 and Au/CaF2/n-Si(111)7×7 in UHV. In both cases, the topography of the Au surface is characterized by ≊2.5 A˚ height terraces, stacked in several stages, with rounded shapes for Au/Si, and hexagonal shapes for Au/CaF2/Si. BEEM up to tip voltages of 8 V on Au/Si is not altering the ballistic transmissivity, in contrast to previous work on Au/Si interfaces which involved chemical preparations of the Si surfaces. The shape of the BEEM spectra on Au/CaF2/Si depends on spectral features of the density of states of the CaF2 thin film.