Wacker-chemitronic Gesellschaft Fur Elektronik-grundstoffe Mbh

Wacker Chemitronic Gesellschaft

Helene Prigge

Gerhard Brehm

Anton Schnegg

Robert Rurlander

Josef Lang

Herbert Jacob

Michael Schwab

Reinhold Wahlich

Andreas Englmuller

Hans-Peter Bortner

Harald Hoffman

Fritz Ketterl

Hans P Bortner

In the chemo-mechanical polishing, in particular, of semiconductor wafers, he abrasion and the geometrical quality of the wafers decreases with increasing service life of the polishing cloth. This can be prevented by treating the polishing cloth in each case after the polishing operation in a manner such that a pressure field is impressed, essentially without mechanical stress, on the polishing cloth, which pressure field causes a treatment liquid to flow through the interior of the polishing cloth and in this process the residues produced during polishing are rendered mobile and removed. A baseplate placed transversely across the polishing cloth and having a flat working surface provided with exit openings for the treatment liquid is suitable for carrying out the process. In the treatment, the treatment liquid is forced beneath the baseplate into the moving polishing cloth so that the latter is gradually traversed by the zone through which flow takes place.

Process for treating polishing cloths used for semiconductor wafers

Semiconductor slices, in particular having the surface polished on both ss, can be provided with a surface which effects the formation of gettering centers. These centers include stacking faults and/or dislocation networks in subsequent thermal treatment steps by a pressure loading being exerted on them with the aid of an elastic pressure transmission medium which causes local pressure inhomogeneities. A material erosion, for example in the form of scratches, is not necessary in this process. Advantageously, the treatment is carried out during a template polishing step in which a suitable pressure transmission medium is in contact with the rear side of the slice. The process makes available semiconductor slices with gettering action on one side which have a high surface quality on both sides.

Process for the surface treatment of semiconductor slices

Semiconductor wafers, in particular, silicon wafers, with differently poled front and rear sides and high geometrical quality can be fabricated by double-sided polishing if the wafer surfaces are differently polarized during the polishing process. This can be achieved in a simple fashion, in that during polishing, an electric field is set up between the upper and lower polishing plates. This can be accomplished by providing the upper polishing plate between the plate surface and the polishing cloth with a thin conductive layer insulated with respect thereto, on which a voltage can be impressed, while both polishing plates are grounded to the frame.

Process and apparatus for double-sided chemomechanical polishing of

A process for removing contaminants, particularly dopant, from halosilane-containing carrier gases, such as those which are produced in the production of high-purity silicon. The process of the invention is perferably carried out with aid of zeolites which has a low proportion of aluminum and are used in the anhydrous state by bringing the zeolites into contact with the carrier gases. Zeolites, after use, can be regenerated and re-used by increasing the temperature and/or decreasing the pressure of the procedure.

Process for removing gaseous contaminating compounds from carrier gases

A process for preserving the surface of silicon wafers after the wafers are polished in a conventional polishing operation by converting the wafer surface to the hydrophobic state, in particular, by polishing, or with hydrofluoric acid and treating immediately afterwards with a reagent, e.g., alcohols, organosilanes or silanols and preferably in aqueous solution. The wafer becomes coated in this process with a protective layer which inhibits surface deterioration, and also permits long storage times.

Process for preserving the surface of silicon wafers

A process and apparatus for etching semiconductor surfaces, in particular, ilicon, with a mixture containing nitrogen-oxygen based compounds as oxidizing compounds, hydrofluoric acid as the component which dissolves the oxidation product, and sulfuric acid, optionally with phosphoric acid added, as a carrier medium. This mixture makes it possible to design the process as a cyclic process in which oxygen supplied to the system ultimately effects an oxidation of the material to be etched, and the product of its oxidation is removed from the circuit. The process is noteworthy for its low usage of reagents and because it is not harmful to the environment.

Process and apparatus for etching semiconductor surfaces

A polishing process in which haze-free semiconductor wafers can be obtained in a single-stage process in which an initial phase of the polishing operation is carried out in the usual manner in the alkaline region. This initial stage is followed by a final phase in which polishing is carried out, at a pH of 3 to 7, in the presence of additives in the polishing agent which reduce the amount of material removed by polishing. Consequently, it may be possible to dispense with polishing agent components which act mechanically. Both phases can be carried out on one and the same equipment without interrupting the polishing operation.

Method of haze-free polishing for semiconductor wafers

The liquid or gaseous substances, such as hydrogen or trichlorosilane, enntered in the gas-phase deposition of silicon may contain n-type doping impurities which can be removed by adduct formation with silicon, titanium or tin halides. The impurities can be liberated from the adducts by thermal treatment and finally removed. The halides left behind are capable of again forming adducts and are again used to remove the impurities. The process can consequently be operated cyclically and is remarkable for the low quantity of chemicals required and for its ecological harmlessness.

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Unterschleissheim, Germany

Helene Prigge