Any body know that how to clean the Substrates of MgO and Si with onside Polished. There are several method that i know about like put the substrate in Nitrogen environment for long duration, some use IBE cleaning, lithographically cleaning,Lithographically processed but cleaned with a final IBE, chemical etching, and Heat treatment.
But I want some low cost and effective methods which can produce the same as above result as i mention above. please share your opinions and ideas
I have cleaned Si subtrate for deposite ZnO thin film. Then is my method in detail: "Si substrates are cleaned ultrasonically in distilled water, in acetone, in ethanol in 10 minutes for each solvent; in a solution (H2O:H2O2:NH3OH =5:1:1 in volume), and in solution (H2O:H2O2:HCl=5:1:1 in volume) in 15 minutes for each solution." Good luck
thanks , but I know this method. I need to clean so deep that we can obtain the pure layer of the substrate, without contamination
I doubt that you can be both very clean and very cheap. It already starts with the quality of the solvents (and work environment!) which also may induce cost. In case of silicon: what is the wafer orientation (do you care at all)? And do you need to remove the silicon oxide before proceeding to growing your structures?
For Si(111) there exist chemical ways to produce hydrogen terminated Si(111). This is fairly stable at ambient temperature and the hydrogen will desorb aroud 500°C (if I remember this right). When you do this in ultrahigh vacuum, You are left with an unreconstructed clean Si(111) surface.
For what we do, we start with the 7x7 reconstructed surface and therefore skip the hydrogen termination chemistry. After multiple solvent cleaning (similar to the above) we insert the piece of wafer into UHV and do an annealing sequence lasting several hours (typically over night), by passing a current through the specimen. (While UHV of course isn't cheap by any means, direct current heating in principle is.) The rule of thumb is to heat to about 700°C or so without the vacuum ever be worse than 10-9 mbar. When this is completed, we flash off the surface oxide and follow the well-established thermal procedure to obtain the 7x7 surface.
One of the biggest problems with cleaning substrates before thin film deposition is actually drying off the solvent used without leaving drying marks. Typically the substrate is washed and sonicated in water, then acetone, then isopopanol (if the substrate has been severely mistreated you may need to do some light swabbing to loosen any dried on particulates and residues).
For the final stage it should go through a process of "vapour degreasing" (see P51 "Optical Thin Films User handbook" J.D. Rancourt). In the simplest case this can be a glass beaker, the substrate is sat at 45 degrees higher up the beaker, on some form of support. The top surface (which is kept wet from the preceding cleaning steps) is then washed with clean isopropanol from a wash bottle. A metal plate is put onto the top of a beaker as a lid, and the beaker set on a hot plate so the isopropanol slowly boils. As the vapour reaches up the beaker it will condense and run off on the cooler surfaces, including the substrate material. Finally it will drip from the metal "lid". Once the sample has been washed in this way, take the beaker off the hot plate and leave to cool. (If the lid is removed too soon, drips will form on tweezers used to take out the sample.)
Of course use caution with the fumes, and well away from sources of ignition! To more thoroughly drip clean the sample, you can mount an electronics type heat sink onto the lid to assist in condensing the vapour, positioning it to drip onto the top section of your sample. You can even add water cooling to the heatsink. As well as preventing drying marks, as it is the condensed vapour washing the sample, this method also ensures the solvent has no particulates in it.
Once cleaned you might also consider a period of baking the sample > 100C (either in or out of vacuum). A cheap ceramic radiant heater is very effective for this (more so than a high power halogen bulb). This process helps remove any volatile material stuck to the surface of the substrate that will cause bad adhesion and pin holes in your thin film.
1% aqueous solution of hydrofluoric acid will easilly remove native oxide on silicon within one minute. If your silicon was oxidized by a high temperature treatment you may need more time or higher concentration of HF.
I offer the cleaning based on some deionized water. Use the Ultra Sound cleaning in some deionized water. Then use drying by blowing N2 at 40 C when rotating a substrate.
I wish good luck.
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