Hi,

You can use a furnace having a cold resistance of about 5 ohms. The electric power supplied to the heater is about 150 W . The heating element, based on the indirect principle of  heating by  resistance, may consist of a  coil made with a nichrome wire wound around your sample. To minimize heat losses, it is necessary to equip the furnace for example with concentric   reflectors (screens) which may consist of a polished molybdenum strip, 0.1 mm thick, in order to reflect a portion of the heat flux. The temperature measurements of the sheath of the heating element can be performed by a chromel-alumel thermocouple. The heating element must be connected to the heating circuit via supply wire of adequate current. This furnace was manufactured by a lab technician. I could get a pressure of 10-7 mbar after 24 hours of pumping.

It all depends on what you want to heat. I use a normal heater and put on it plate. Take the best sheet steel and the heater with the possibility of voltage control. Thermocouple too arbitrary. Only if you have a vacuum connections to hook up the wiring. Annealing in vacuum is not easy.If you have any questions please write. I do it often.

I want to increase the temperature of my substrate(most of the time silicon is our substrate) in the sputtering system. I like temperature around 400 or 500 oC . I examine my  sputtering with mica based heater and we had a little problem with controlling temperature (competently different temperature curve vs time and voltage in and out of vacuum) and i also checked the IR based heaters ceramics knows as vacuum heater. In the later one we got huge problem with pressure. When the vacuum heater is Off we have a little problem and when it is one it change pressure from 5E-4 to 5E-2 . What should I do.?Do you think that I should use IR based heaters or mica or something else? I want it to be cheap and effective.

thanks

masoud

Hi,

You say :"when the vacuum heater is Off we have a little problem and when it is on it change pressure from 5E-4 to 5E-2". It is a normal behavior. During heating, degassing increases and the pressure also increases. If I understand correctly, your work pressure is about 5 E-4 Torr in vacuum. So if you can get a pressure of 5 E-6 Torr before turning on your heater, it might work after annealing your sample. I could reach 5 E-9 mbar at room temperature , but during heating,  it has never exceeded 1 E-7 mbar. You can take a look at my works. They are on Research Gate.

If your sample is large enough, there is another way for annealing. You can heat your sample by electron bombardment. But this assumes that you have a HV supply (2-3 kV). I'd give you more details if you are interested in this method.

Hi,

I plan to use heater as substrate heating during sputtering. I vacuum the system (in normal) up to 5E-4 and then fill it with Ar gas up to 5E-2 and start sputtering. Now with heater I get to 5E-2 without gas. What make me worry to let the system vacuum till E-6 and then bring it up by heater ON and then Ar is the degassing of heater and since I want to use Ar sputtering, these degassing from heater can make effects on my substrate,probably. ( i think I am not sure). In this case what should I do?

thanks

masoud

While heating the vacuum level changes. You have to be pumped out more. It is not so easy to maintain vacuum and temperature. Constant temperature is simple when constant conditions. The vacuum changes at a temperature which is normal for gases.The temperature is not a problem. The problem is with the quality vacuum. Everything also depends on how big the sample. For small samples should not be a problem. You can then use the heater covered with mica or resistance wire wrapped in coated sheet (as I am). It is cheap and easy solution.

Hi,

If I understand correctly, the heater would be contaminated by Ar. So it must be degassed. For this purpose, you have to remove firstly the sample from the vacuum chamber, then you start to degass the heater by switching it on, for a sufficient time of pumping, till you reach a good pressure. Then, you switch off the heater which will cool down to room temperature.Then, you break vacuum. After that, you put the sample again in the vacuum chamber and you repeat the pumping process. And you can then heat up again. Good luck.

Hi, 

Thanks for all responses. I use all of them and it almost work. I still have problem with it if i want to go beyond 200 oC. But another question i have now is that can I use 220VAC to heat up my heater during sputtering. If I am correct the plasma is conductive environment and this means it may connect with 220V and we have huge problem. If I can use 220V AC, how? If not how much watt do i allow to enter to the chamber during plasma in DC form? What current?

thanks

Masoud

Hi,

I'm glad for  your research which advance. To power the heater, instead of using the 220 V AC, you can use a set of three 12-volt batteries connected in series to provide the heating element a power of about 150 w.

Hi Masoud,

We have been using an annealing furnace with halogen heaters and we can easily check the temperatures by PID controllers. As I understand, you would like to use it in situ sputtering process. In this case, again I strongly suggest you using halogen heaters. With this kind of heaters, you can go beyond 1000 C. We use the same system in our sputtering system which was fabricated by a Turkish company, Vaksis.

If you like to take a glance at the results of the annealing of thin films by this tool, you can explore the following article.

All the best.

Article Conventional and rapid thermal annealing of spray pyrolyzed ...

Hello everyone. I have a similar issue as this. I want to heat up a vacuum vessel using solar concentration lens. Will I have heat gain in then substance inside. I fear that at vaccum condition, heat transfer will be limited. Solar lens can achieve a temperature of 600oC, so will my substance inside the vessel attain that temperature or higher in vacuum condition

You need to be very careful heating up a vacuum chamber above the 200 C range as it needs to be designed to operate at these elevated temperatures. Besides simply desorbing water vapor, if you are using Viton seals of any kind at those temperatures, out gassing from the o-rings will cause virtual leaks, slow your pumping speed and can potentially damage the Viton and contaminate your substrate. For a chamber going to 400 C you should probably be using nothing but metal seals in your vacuum chamber. Heat in the form of radiated IR works well in vacuum, either using heat tapes, ceramic heaters or Quartz lamps with a PID temperature controller and a sensing probe near or on the substrate. Vacuum does not interfere greatly with radiated or physically conductive heat transfer, however it does eliminate any heat transfer by convection.

You can focus the heating (by photons or electron bombardment) on your sample, without heating up the ultra-high vacuum chamber. You must use a window made of quartz , or preferably sapphire, if possible.

I heated graphite tiles over 1000 ° C without heating the vacuum chamber. Obviously, you have to work with a lot of care. The important thing is to know what pressure you are working on.

Hi,

anyone knows where i can get halogen heater with focused beam?