Mitsubishi Electric Uses Flip-Chip Bonding to Achieve 40 Gigabit per Second Optical Modulator and Photodiode
Announcement posted by Mitsubishi Electric Australia 07 Feb 2002
Mitsubishi Electric has introduced a 40 gigabit/second optical modulator and photodiode which uses flip-chip bonding to increase speeds of optical transmission systems. The new technology is ideally suited to 40 gigabit/second transceivers, used in overland optical trunk networks and rapidly expanding metropolitan networks. It is also expected to facilitate cost reductions in next-generation submarine cable networks.
The key components of required optical systems are a modulator to convert electrical signals to optical signals, and a photodiode to reverse the process at the other end. Between them, these components determine the upper speed limit of the system in question, said Tatsuo Hatsuta, head researcher at Mitsubishi Electrics Information Technology R&D Center. Until now, this limit has been low due to the parasitic capacitance of optical semiconductor and electrical IC chips. Inductance between the wires inside the package also placed a low ceiling on performance.
The new product has two characteristics that improve waveform characteristics: a novel optical semiconductor chip structure and superlative flip-chip bonding technology. Cost reductions, difficult to achieve with existing wire bonding techniques, can be realized thanks to homogenous high-frequency characteristics.
With the steady progress of the information revolution, demand has been rising for ways to minimize communications costs while simultaneously coping with the rise in the volume of data being transmitted across networks. Accelerating beat rates per transmission route is an important way of bringing this about. The new modulator/photodiode is expected to accelerate the adoption of 40 gigabit per second optical transmission systems.
Mitsubishi Electric was able to produce the new technology based on its overall strength in semiconductors. It was after understanding the problems of low parasitic capacitance of optical semiconductors and inductance between wires that Mitsubishi Electric technicians came up with the idea of adapting flip-chip bonding, a technique often used in IC bonding, for use with optical elements. Achieving this required the creation of sub-micron optical connections, which in turn necessitated the development of original element manufacturing and bonding technologies. Sample products are due to be delivered to potential customers in May 2002.
Technical Summary
-Waveform improvements due to high frequency flip-chip bonding:
Modulator: Flip-chip bonded to the ceramic microwave circuit.
Photodiode: Directly mounted on the preamp IC chip, a world first.
-Reduction of parasitic capacitance:
Modulator: Semi-insulated Fe-doped InP substrate section allows 20% reduction in parasitic capacitance
Photodiode: Waveguide detector area reduces capacitance to less than 0.1pF.
The key components of required optical systems are a modulator to convert electrical signals to optical signals, and a photodiode to reverse the process at the other end. Between them, these components determine the upper speed limit of the system in question, said Tatsuo Hatsuta, head researcher at Mitsubishi Electrics Information Technology R&D Center. Until now, this limit has been low due to the parasitic capacitance of optical semiconductor and electrical IC chips. Inductance between the wires inside the package also placed a low ceiling on performance.
The new product has two characteristics that improve waveform characteristics: a novel optical semiconductor chip structure and superlative flip-chip bonding technology. Cost reductions, difficult to achieve with existing wire bonding techniques, can be realized thanks to homogenous high-frequency characteristics.
With the steady progress of the information revolution, demand has been rising for ways to minimize communications costs while simultaneously coping with the rise in the volume of data being transmitted across networks. Accelerating beat rates per transmission route is an important way of bringing this about. The new modulator/photodiode is expected to accelerate the adoption of 40 gigabit per second optical transmission systems.
Mitsubishi Electric was able to produce the new technology based on its overall strength in semiconductors. It was after understanding the problems of low parasitic capacitance of optical semiconductors and inductance between wires that Mitsubishi Electric technicians came up with the idea of adapting flip-chip bonding, a technique often used in IC bonding, for use with optical elements. Achieving this required the creation of sub-micron optical connections, which in turn necessitated the development of original element manufacturing and bonding technologies. Sample products are due to be delivered to potential customers in May 2002.
Technical Summary
-Waveform improvements due to high frequency flip-chip bonding:
Modulator: Flip-chip bonded to the ceramic microwave circuit.
Photodiode: Directly mounted on the preamp IC chip, a world first.
-Reduction of parasitic capacitance:
Modulator: Semi-insulated Fe-doped InP substrate section allows 20% reduction in parasitic capacitance
Photodiode: Waveguide detector area reduces capacitance to less than 0.1pF.