2 Methods for Double Side Polished Coated Germanium

Double side polished coated Germanium is commonly used for flat germanium windows or substrates in infrared optical systems.

For double-sided polished coated germanium, most factories utilize surface-by-surface polishing (polishing one side, then the other) processing methods, including waxed polishing and wax-free pad polishing.

1.Wax Polishing 

Fix the main side of the wafer down on the ceramic disk with wax, then carry out the backside polishing, after polishing, heat the ceramic disk to dismantle the wafer, waxing. Should protect the polishing surface, and then again on the plate, the polishing surface down on the plate, throw the main surface qualified after unloading the piece, wax, cleaning during this process.

Since there is only a thin layer of wax between the wafer and the ceramic disk, and the wafer and the ceramic disk are tightly adsorbed, it is very easy to cause displacement between the wafer and the ceramic disk when unloading the wafer, so it is very demanding on the operator’s technique and proficiency.

Polished coated Germanium

2.Wax-free pad polishing method

The wafer on the disk first throw the back side, the back side of the qualified unloading, shake dry, in the polished back side of the uv film, the film face down on the disk, throw the main side of the qualified unloading, shake dry, uncovering the film, cleaning.

Due to the need for film processing, will use the blade chipping film, so that when chipping and uncovering the film will have the possibility of chipping to the edge or face of the wafer, resulting in cp and deep s defects, these defects belong to the external forces caused by the general scar are deeper, it is difficult to repair, very much affecting the wafer’s qualification rate, due to the polishing of the film as a protective layer, the film is a gum, will remain on the face of the polished coated germanium, the polished impurities, particles of sticking pollution, and more. Need to clean to remove, not easy to clean.

CNGE adopts double-sided polished coated germanium method, due to the stable amount of drop, uniform reaction, can drop the amount and surface quality of both, with double-sided polishing with only one procedure to be able to complete the polishing, to ensure that the ttv in the qualified range, the wafer thickness is uniform, simplify the method of steps, reduce the consumption of auxiliary materials, save labor, remove the polishing of unnecessary impurities generated by the adhesive contamination, improve the efficiency of the polishing and the quality of polishing, to Improve the stability of polishing; processing time is short, good quality, high efficiency and processing consistency, can be mass production of products.

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