MKU-Products for Wire Slurry Sawing of Rigid Materials
In the modern semiconductor industry and in many other application areas, wafers and similar work pieces are today predominantly manufactured by means of wire slurry sawing. In this process a special lapping suspension (slurry) is applied. The efficiency of this slurry is strongly dependent on the properties of the carrier-fluid used to make the slurry.
MKU-Chemie GmbH in D-63322 Rödermark (Germany) is one of the most competent and experienced producers of such carrier fluids in Europe. Special fluids of this type have been developed by MKU-Chemie since many years, based on long-term research and intensive practical testing. These fluids are based either on special mineral oil fractions or on particular glycols which are compounded with special additives to obtain a maximum of performance. Slurries made with these carrier fluids have remarkable features in terms of detergency, excellent surface quality, high cutting rates (cm²/min) and low shear rates resulting in low energy consumption. Related to these slurries, MKU-Chemie developed also novel water-soluble cleaners, available as high alkaline or neutral solutions. These „Alkalox“- and „Neutralox“- cleaners efficiently remove all the adherent slurry residues from the wafer surfaces (even when carrier fluid is based on mineral oil), leaving a clean quality wafer. MKU-carrier fluids and cleaners are finely tuned to complete each other to an optimal performance.
In the following these products are described in more detail.
A. Carrier Fluids for the Production of Wire Sawing Slurries
These carries fluids have been developed after intensive research and practical cutting test series, to be used for the production of wafers from semiconductive materials on wire slurry saws. There are two different product lines, structured for different application areas:
Dionol® – line: Dionol® Extra V 1591-1 – 1591-15
These fluids consist of different selected mineral oil fractions compounded with proprietary additives. They deliver high efficient slurries, offering a very sharp grain-grip and very low frictional losses.
Betronol® – line: Betronol® MF V 1016 – MF V 1016-15
These carrier fluids are based on especially selected glycols and are predomi-nantly used in the photovoltaic industry where excellent results are obtained regarding cutting rates, surface quality, and efficient grain recycling.
Beside of an efficiently reduced energy consumption (more than 30 %), these products are characterized by a very high chemical stability and by an easy control of the corresponding mechanical cutting operation. The following properties should be emphasized:
– very good heat conduction => cool slicing process
– low surface roughness (Ra) }
} => high quality
– reduced subsurface damage (SSD) }
– small grain volume and grain size }
} => high economic efficiency
– high slurry life time }
Regarding the last point, it is also important to understand that slurries made with products from MKU-Chemie only have a low tendency for slurry sedimentation. For this reason, the formation of hardened sedimental conglomerates does not occur, even when the slurry is not used for a longer time.
B. Cleaners for Work Pieces Cut by Wire Slurry Sawing
After slicing the plates by wire slurry sawing (for example of large silicon wafers), the work pieces stick intensively together and are heavily contaminated by residual slurry layers. In order to make separation and cleaning an easy follow-up process. In addition, MKU-Chemie has developed special cleaners which work efficiently, and even in case of mineral oil-based slurries best cleanng results are obtained. The complete cleaning and degreasing is obtained by an optimal chemical adjustment of the cleaner to the MKU-carrier fluids. MKU-Chemie provides the following products in particular:
This newly developed detergent is an alkaline cleaner, which allows separation and basic cleaning of wafers and similar work pieces, by some hours immersion in a solution of 18- 50 % Alkalox 580. Thus very high degrees of cleaning are obtained so that further treatments with alkalines and/or mechanical processes are not necessary.
This special neutral cleaner is an improved modification of Alkalox 580. It is designed to comply with increased demands for chemical purity of surfaces (e.g. hightech-silicon wafers).
The final cleaning process is carried out by means of a subsequent Ultrasonic- or spray-equipment with a solution in a concentration of 2 – 10 %. In order to obtain an optimal result it is absolutely necessary to use both, MKU-carrier fluid for the wire sawing process and subsequently MKU-cleaner for the cleaning process.
There ist also another reason that accounts for the use of the new MKU-detergents: In future, aggressive media for the cleaning of hightech wafers might be prohibited by law. In this case, the described Neutralox products can be used as an already available alternative.