I want to grow epitaxial semiconductor films on wafers heated to 700-1200C on a graphite susceptor.
Are you sure you want to do it this way? We use "direct current heating" of semiconductor wafers, i.e. pass current through the wafer itself. In practice, this means passing about 13A through a piece of Si of dimensions 5mm by 10 mm to reach 1280°C (thermally removing the oxide layer from Si(111) ).
Of course, this requires that you have a holder with isolated ends. Also, the larger the width, the more current is needed. What I consider the biggest advantage is that the wafer is actually the hottest piece of material in the chamber so that desorption from other parts is much less severe than with any other solution we tried before.
Hello Kai,
I like your clever method, but it would be difficult for me because I have multiple, 75mm diameter wafers. The equipment is already set up. I want to upgrade the RF power supply and am looking for advice on the best frequency.
Brad
I get your point. Also, for entire wafers, tremendous DC currents would be needed. Have no experience with inductive heating, though. I imagine that optimum frequency might rather be a functin of geometric setup (in conjunction with graphite properties) than of graphite (as such and alone). In the end, what I guess you will be doing is impedance matching. If resonance conditions are to be met for optimum coupling then I would try to figure out the equivalent circuit.
Hope you will find someone able to give more specific advice. Good luck!
I think a matchbox with a coil and a tunable capacitor would be helpfull anyway, to minimize the reflected power. But I can´t help with the right frequency either. I guess several frequencies would be possible. For high frequencies 13,56 Mhz are common. For the graphite susceptor a Silicon carbide coating is neccessary, otherwise autodoping might occur.
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