MF pulsed DC bias power supplies
Unipolar Pulsed DC Bias Power Supply
We offer MF pulsed DC bias power supplies for substrates biasing during film deposition or for ion etching prior to deposition. As for the magnetron power supplies, we have developed two types of unipolar, MF pulsed bias power supplies – which support pulsed mode only, working at fixed 60 kHz or supporting both DC and pulsed mode, with adjustable pulse frequency in the range of 55 to 110 kHz and duty factor, adjustable in the range 0.1 to 0.7. All of these bias power supplies work at voltage stabilized mode only. Active arc suppression schemes are built in to prevent arc appearing and thus substrate damage. Typical output voltages 0 to –250V are used for biasing during deposition and fixed – 1000V – for ion etching prior to deposition, the “plus” pole is grounded.
Bipolar Pulsed DC Bias Power Supply
Since the second half of 2006 we developed our own design of asymmetric bipolar pulsed bias power supply. The power supply works as a voltage source, negative pulse amplitude can be adjusted in the range of -20 to -200V DC, the positive pulse amplitude is within the range of +15 to +50V DC and is proportional to the negative pulse current magnitude. Fixed low power +15V internal power supply provides energy for positive pulse formation in case of low current applications, when the magnetic energy, stored in the output inductor is not sufficient to form positive pulse. When the average value of the output current is high enough, in the output inductor is stored enough energy, which we use for charging filtering capacitor and subsequently this energy is used to form positive pulse. Thus we provide better conditions for recharging of the sheet charge in case of insulating layer’s deposition. Working frequency range of our power supply is 50 to 100 kHz, the pulse duty cycle can be adjusted in the range 10 to 42 per cent, equal for negative and positive pulse, thus adjusting the output current value. During the negative pulse power supply acts as a voltage source with current limiting and limited current increase rate and during the positive pulse duration output acts as voltage source with maximal over-current protection only. This mode of performance provides fast and complete recharging of the surface charge. Three-level arc suppression circuitry for both pulses provides 600 ns fast arc suppression, thus preventing substrate surface damage, even for sensitive materials.
We are able to satisfy variety of specific customer requirements designing and manufacturing custom designed bias power supplies. Our asymmetric bipolar technology can provide an output power up to 1kW, with maximal output voltage -250V and maximal average output current 5A. We are able to deliver unipolar power supplies with output power up to 2,5 kW, as well.
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