RF Power System FAQs

Bdiscom Model BDS-HF-300AFP

• Problem: When turning ON the RF power output, the value starts at the set-point and then falls to 001 watts – it should be noted that the plasma does ignite and the matching network does properly tune. Solution: Use the front panel controls to select the DC Bias mode and then raise the DC Bias set-point value to 500 or greater.  If this setting is too low, then the RF power will fold back to try an reach the low set point. Please refer to the BDS-HF and BDS-AMN owner’s manuals for detailed information.    Link to BDS-HF pages  Link to BDS-AMN page
  
  
• How can I connect the Common Exciter (CEX) – The Model BDS-HF includes both input and output connectors for the CEX connections. The connector types are SMA female. See the image to the right. If both generators use type SMA connectors, the connection cable would need to have SMA male connectors on each end. If the other generator has a type BNC female, then the connection cable will need to have an SMA on one end and a BNC on the opposite end – or you can use a SMA male > BNC female adapter and then use a more common BNC male>male cable. The output waveform is a sinewave specified at 1Vrms (2.83Vpp) @ 13.56MHz. The CEX input will accommodate either a sine wave or square wave signal from 0.25 > 1.5Vrms (or 0.71 > 4.24Vpp). The typical connection includes connecting the CEX cable from the sputter generator’s CEX output (master) to the substrate bias generator’s CEX input (slave). When the CEX input senses the master’s signal, it automatically switches into the slave mode. Please note that the length of the CEX coax cable will influence the phase difference between the  master and slave power signals. In some applications the CEX cable length may not make a large difference and with other applications, it may. Selecting the correct cable length (by trial and error) will result in: smoother match network tuning and, more developed DC bias for less applied bias (slave) RF power. Trial and error testing may include the use of different length cables or the use a variable phase shifter.  Please note that the BDS-HF’s internal connection cable is 11.81102″ (30cm) long of Teflon insulated cable – this length may be used to calculate the required coaxial connection cable length (phase delay).
  
  

• Manitou Systems Model PB3

  Why won’t my PB3 power up?

  Is the unit connected to the correct AC mains voltage? 

  Is this circuit live? 

  The PB3 uses an IEC (HP) type AC mains input module. This module includes a filter and fuses. Are the fuses OK? Please look for the label on the side of the enclosure as this is where the necessary AC mains voltage level is displayed. The necessary voltage is 187>240VAC 50/60 Hz single phase and only 115VAC is applied, the internal circuits will not operate correctly.

  How can I power my PB3 with other than the rated AC mains voltage ?

  The PB3 can safely be operated form other AC mains voltages when used with a step up/down transformer. This transformer is connected between the user’s wall socket and the PB3 AC mains input. 

  If you desire to operate it from a 110 VAC power source, please use a 115/230 step up transformer. For the 600 watt  (RF output) model, we recommend using a Stancor model GISD-1000 – this is rated at 1000VA of capacity with shielded and grounded power cords. You may also need to provide additional wiring plugs and receptacles for your application/installation. These can be purchased at a local electrical supply or through distribution. The recommended transformer can be purchased from Newark Electronics PN 01F1009 www.newark.com.  

  Why won’t the Interlock LED light ? 

  If the unit powers up; cooling fan runs and front panel display operates you should verify that the interlock shorting plug is installed. The pre-wired plug provides the proper wiring to enable the unit’s software to boot and operate normally. If this plug has been re-wired; please check that the wiring scheme follows the schematic in the PB3 owner’s manual.   

  Why do I need an external interlock connection?

  Questions relating to connection cables

  How long can I make the RF output cable ? (RF generator output to impedance matching network). 

  We suggest that a 1/4 wave cable (typically 12 feet in length for type RG 8 or 213 polyethylene insulated) be used. This recommendation is based on the RF matching problems that may exist with longer cable lengths. If the 12 foot is not long enough, then the cable should be extended in 1/4 wave (12 foot” lengths. You should also plan to use a high quality polyethylene or Teflon coaxial cable (type RG-213 or RG-393).

  With the above said; we do believe that some customers do use other cable lengths with good results. Remember that each application has its own impedance matching personality. Therefore, it is best to check with a Manitou Systems engineer if you encounter trouble with your application.

  Plasma Application Questions

  Why can’t the Reflected power be tuned to zero watts ?

  Why won’t the plasma ignite?

  When used in substrate bias applications, is the RF Power or DC Bias control mode best ?