I am not sure if you can use the roughing pump for both the purposes, but I think it might be tricky during crossover. I can't comment much on it as I've never designed a diff-pump system before.

Even for electroplating purposes, people generally use a seed layer (typically of the same metal) for a good coat, which is evaporated. Other than evaporation or sputter deposition, I'm not aware of other methods.

What metal do you wish to deposit? 

Yes thermal evaporation can be done on SiO2 surfaces.

Depends on the metal you are evaporating, and how well it sticks to the SiO2 surface.

Sometimes buffer layers are used for Au-Cr, and Pt-Ti, Au-Ti etc., You can refer to the literature, depending on the electrode materials (Au, Pt, ) accordingly thin buffer layers are to be deposited. Normally Au-Cr bilayers are the most common metallisation system which can be easily developed by Thermally evaporated.

coming to the second question.

Normally a rotary pump is used for both roughing purposes, and later as a backing pump for a diffusion/Turbo pump.

rotary pump as a roughing pump is connected to the chamber directly through a roughing line. Through a roughing valve.

the same rotary pump when it is required to be used as a backing pump, it gets connected to the backing pump (Diff/Turbo), through a backing valve.

A single valve system can be used as a roughing/backing pump., For example when swung to the RHS (right hand side) it acts as a roughing valve, and thereby connects the chamber to the rotary pump directly for roughing purposes.

When swung to the LHS it connects  the rotary pump through  backing valve to the diffusion/turbo pump.

To keep my description simple the roughing line and the backing lines are separate. In each one of the these lines you can have a single valve which will act as a roughing vale in the roughing line. or

as a backing valve in the backing line.

Only one valve should be opened, and the other should be closed., and vice versa.

 Both valves should not be opened similtaneously.

You should be clear about the way these lines (roughing & backing) are designed and where to locate the valves.

Yes a single rotary pump can serve as a roughing and a baking pump.

Actually you need a diagram to understand clearly what I have described above.

Maybe at a later stage I can send you one such diagram.

Prof. K. Sreenivas 

Thermal evaporation always needs a vacuum system.  Or in other words you are able to deposit metallic films by thermally evaporating them only in vacuum.

I don't think you can do metal evaporation at atmospheric pressure.

to evaporate you have to melt the material at a high temperature, and at atmospheric pressure (without vacuum) you will simply oxidize the metal, and it will not evaporate.

So tha tbasic philosophy during thermal evaporation is to do it under vacuum.

K. Sreenivas

Dear Dr. Matthew Hartensveld

Have a nice time and good day

There are no ways for thermally evaporated any material on SiO2 without a vacuum system. The vacuum process is an essential condition for the physical vapour deposition (PVD) technique. Vacuum prevent the molten material from their oxidation process.

But for metals the evaporation process may be very hard due to that the high evaporation temperature (Tevap.) which sometimes reached the thousands. In other words Tevap. may be higher than the melting temperature of the used evaporation boat (whether it is a tungsten or molybdenum). Therefore the Flash evaporation process is Preferable and favorable in case of the deposition of metals and their oxides.

Good luck

Thank you for the replies. I definitely plan to build a simple thermal evap system, and it extremely interesting to hear about AACVD I plan to look into it further. I have tried electroless deposition via HF + AgNO3 on Si and GaAs which is a very easy process which will only stick to the bare substrate, to coat oxide apparently you can pretreat the surface with SnCl2 to get silver to deposit: http://www2.bren.ucsb.edu/~dturney/port/papers/Modern%20Electroplating/05.pdf

Yes you could use electroless deposition to get a seed layer on any surface, and then grow a thicker layer on top of that by electrodeposition (if you need a thick layer). That way you do not need a vacuum system. On the other hand an evaporation system is very convenient to have if you need to apply metals more often. Be aware however that evaporation is a directional technique, so if you have 3d features that you need to coat the metal will hardly deposit on sidewalls and not at all at the bottom of structures.

Electoplating after the initial electroless dep is a great idea, as the electroless method seems to not from a continuous film. 

I do not think electrodeposition will work if your electroless film consists of isolated islands. For electrodeposition you need good electrical contact to the surface on which you are growing.