Attache is a photo of a magnetron sputtering system.
According to the researchers working in the lab, the maximum working temperature in the chamber is 350 C. Nevertheless, for some experiments, higher temperatures are required.
The thermocouple is freely in the space between the heater and the pedestal, so it does not show the actual temperature and when we put it under the holder, the temperature was lower by ~50 C.
The lamps in the heater have no labels. What can hinder us from increasing the temperature in the chamber? Is there any way to recognize the model and manufacturer of the lamps?
Hi Michael,
In vacuum using heating lamps you have only to consider radiation which heats up a holder. Emissivity is important and making the holder really black helps increasing the temperature. Is the reason you do not attach the thermocouple to the holder because of electrical shorts/ground issues? If so, consider using a ceramic fitting tightly around the thermocouple and fixing this to the holder. In this way you get a much better temperature measurement. When the holder is made black and your temperature is still too low, the IR-light output of het lamps is just not enough and you need to find other ones.
You can certainly increase the substrate temperature. There are radiant heaters commercially available that can go up to 500 degrees. If you want higher temperatures you can change your heater. A calibrated thermocouple should be kept as close as possible to the substrate holder so that it can measure exact substrate temperature.
You can use radiation lamps housing with reflectors of an appropriate polished metal behind the lamps, and direct the heat towards the centralised substrate platform, and heat up the platform right upto 800 deg C.
Temperature measurement of the substrate platform with a thermo couple is not a good idea, especially (let us say if you have rf plasma based sputtering environment). In this case an optical pyrometer is the best way out with a sapphire probe.
Nordiko company from UK has been making sputtering systems with substrate heaters which go right upto 850 deg C since many decades, and can be conveniently and routinely used (upto 700 deg C), with no problem. I have used some of their designs in my research, and work very well. But yest the whole substrate platform needs special designing, and special construction materials materials which can withstand such high temperatures.
Dear Dr. Pylnev,
If you increase temperatures much above the temperature for which the system is designed, be careful not to damage/destroy the vacuum sealings though. As you can go to 350°C with the system, I guess you have Vitton O-rings in your system. But temperatures of 850°C etc. would require metallic sealings !
Regards,Paul Lippens
Dear Mikhael,
yes, the answers are shedding light to various issues. Be careful.!!
The quartz halogen lamps can be obtained from suppliers. you should first measure what max. voltage and current is supplied to the lamps.!!! Note that changing lamps may vary your current values. High temperature heaters may require water cooling.
if possibble, you can decrease the distance between the lamps to increase the substrate temperature. This is the easiest way. You can also replace the lamps by new ones. You can also Lower your plasma pressure , if possible.
good luck.
Zafer Durusoy
For those who worry about the RF on the thermocouple they can build an RF choke out of a little wire wound choke and a little ceramic capacitor. Chocke in series then the cappacitor in parrallel to ground.
Good Luck John Keller