Koyo Machine Industries Co., Ltd. Grinding Machines for Semiconductor Applications.
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Koyo Machine Industries Co., Ltd. is represented in Europe by
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Grinding Machines for Semiconductor Wafers

Koyo Machine Industries developed several types of grinding machines, used in the semiconductor industry for silicon wafer manufacturing and IC production. Vertical and horizontal spindle systems are used in combination with special designed diamond grinding wheels, that cut just at the edge of the rinding wheel, resulting in high grinding speed and producing low heat. Machines are available for single side wafer grinding in IC production, for double side wafer grinding in silicon wafer manufacturing and for silicon wafer edge grinding. Motor built-in aerostatic air bearing spindles are available for high precision grinding applications.

Single side grinding machines.

Single side grinding machines are used in the semiconductor industry to thin wafers. Typical applications are thinning of SOI wafers or production of chips for IC cards and Smart cards.

single side grinding machine for silicon wafers

Koyo Machine industries can offer several types of single side rinding machines, type Rxxx.

This type of grinding machine can be equipped with 1 or 2 loading stations for automatic loading and unloading.

Double side grinding machines

The latest state of the art in grinding technology are double side grinding machines. Both sides of a wafer are ground at the same time. These machines have a high performance in flatness, roughness and throughput and can replace the lapping process completely - sometimes even the etching process. For advanced production of 450mm, 300mm and 200mm wafers, wire cutting becomes more and more popular, because of the lower costs compared to ID sawing technologies. In 450mm and 300mm silicon wafer production,wire cutting is the leading technology already. Wire cutting creates however wafers with a non-rotation symmetric surface, showing a wave structure and a taper. This geometry is difficult to remove. Lapping requires a rather high stock removal and creates much stronger crystal damage compared to grinding. Single side grinding is also not the ideal technology to remove this wave structure, because the wafer has to be fixed on one side. The geometry of the backside is "copied" to the ground side in this case. Double side grinding combines several advantages. The free floating wafer gets a rotation symmetric geometry with a small crystal damage and very flat and smooth surfaces. Double side grinding is a single wafer operation and all silicon wafers will have the same thickness after this process. Ground wafers can be transferred to polishing without sorting procedures. Full tracking of wafers through all production steps becomes much easier, using this technology. Because of the small crystal damage, the following expensive polishing procedure can be shortened.

double side grinding machine for silicon wafers

double side grinding machine for 200mm silicon wafers

double side grinding machine for 300mm silicon wafers




In the Koyo grinding machines the wafer is kept in a vertical position. Horizontal spindles are used. This design results in a very homogeneous flatness and roughness for both sides of the wafer. Gravity is no factor that can influence the geometry with this setup. In order to get very high performance, the mounting of the wafer and the stiffness of the grinding wheel support are key issues. Koyo developed first a machine model DXSG300 for 300mm wafers that holds the wafer in a vertical position by rollers. Traction is submitted by separate rollers contacting the wafer from both sides. Flatness data of 5µm could be achieve by this construction. The machine is fully automatic, incl. wafer transport from the input cassette to the notch finder, to the grinding station, following a brushing, rinsing and spin-drying step. The wafers are transferred dry and clean to an output cassette. This machine has been developed further meanwhile. The result are the models DXSG200 for 200mm wafers and DXSG320 for 300mm wafers as well as DXSG450 for 450mm wafers. Both machines have a full housing including now also the robots. The main change is a modified wafer holder. The patented system holds the wafer by hydrostatic pressure pads from both sides in a special carrier plate ring. Traction of the wafer is achieved just by a small nose locking into the notch or flat of the silicon wafer. This way, the mounting of the wafer is stress free and flatness data of 0,5µm can be achieved. The accuracy of wafer GBIR is obtained by adjusting the tilt amount of the vertical and horizontal directions of the grinding wheel spindles. The improvement of the GBIR and SBIR accuracy is obtained by changing the contact position of the grinding wheel against the wafer, while the wafer is oscillating vertically.

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