Other

Super Silicon Crystal Research Institute Corp.

Keiichiro Asakawa

Hiroshi Oishi

Junichi Matsuzaki

Shinji Nagatsuka

Shigeru Okubo

Akio Ashida

Hiroshi Kawarai

Shinnji Shibaoka

Hiroo Unozawa

Slurry useful for wire-saw slicing has viscosity adjusted to 400-700 mPa&middot;second at a shear speed of 2/second and of 50-300 mPa&middot;second at a shear speed of 380/second. The viscosity of slurry is measured using a cone and plate type viscometer which can measure viscosity at different shear speeds. Since the slurry sufficiently flows into inner parts of grooves formed in an ingot and consumed for wire-saw slicing due to the viscosity controlled in response to the shear speed, the ingot can be efficiently sliced to wafers or discs.

Slurry useful for wire-saw slicing and evaluation of slurry

A newly proposed wire cleaning apparatus used for removing slurry from a wire, which reciprocatively travels between a slicing chamber and a wiring chamber. The wire cleaning apparatus has a couple of multigrooved guide rollers,rotatably provided at a cover,A slurry receiver,is detachably attached to the cover,A centrifugal force is generated during repeated reciprocative movement of the wire,between the multigrooved guide rollers,and,. Slurry is shaken off from the wire,by the centrifugal force and gathered in the slurry receiver,Removal of the slurry is accelerated by spraying a cleaning liquid W at the same time. Introduction of the cleaning liquid W into the slicing chamber is inhibited by on-off control of the cleaning nozzles,in response to a travelling direction of the wire

Wire cleaning apparatus

An ingot,is sliced to wafers by a wire,which travels around grooved rollers,to,. A tension applied to the wire,is detected by tension sensors,, while vertical displacement of dancer rollers,is detected by position sensors,. At least one of a fluctuation gap of the tension, a fluctuating velocity of the tension, an acceleration of the fluctuation, vertical movement of the dancer rollers,, a velocity of the vertical movement and acceleration of the vertical movement is calculated from the detection results, and compared with a threshold in a calculating circuit,to judge a sign predicting abnormal increase of the tension. When the predicting signal appears, a command signal is outputted from the calculating circuit,to a controller,to stop operation of a wire-sawing machine or to relax the wire,. Since rupture of the wire,is prevented in bud, a wire-sawing machine is efficiently driven for slicing the ingot,with a high productivity.

Wire-sawing machine

If something goes wrong with a wire saw, a personal computer outputs a dial signal to a modem, which dials a calling number of a pager carried by an operator through a telephone system. The sound of the pager notifies the operator of the abnormality of the wire saw even if he or she is not in the vicinity of the wire saw.

Abnormality transmission system for wire saw

A sensor measures a displacement of a sensor, and a control part of a wire saw calculates a sliding load in accordance with the measured displacement and an initial tension of the wire. Then, the control part compares the calculated cutting load with a preset reference value, and controls an ingot feed speed for a drive unit of a workpiece feed table in accordance with the results of the comparison.

Wire saw control method and wire saw

An ingot slicing method and apparatus is disclosed. An ingot is sliced by a wire saw having a wire wound over a plurality of grooved rollers at a predetermined pitch. The ingot is secured to a holder and then pressed onto the wire which is carried along one direction or reciprocatively carried over a plurality of grooved rollers. The holder is shifted along one direction parallel to an axis of the grooved rollers until about a half section of the ingot is sliced. The holder is shifted along an inverse direction during slicing the remainder of the ingot. Thus, a wafer sliced off the ingot has a bowed shape corresponding to a locus of movement of the holder.

Ingot slicing method and apparatus therefor

A wafer 1 has a chamfered edge 2 polished to specular glossiness, and a laser mark for indication of crystal orientation is put on the chamfered edge 2. Another laser mark 4 for indication of specification, production number, identification, etc. may be carved as a bar code on the chamfered edge 2. These marks 3, 4 are carved on the chamfered edge 2 by laser marking which does not put any harmful influences on the wafer 1.

Wafer having a laser mark on chamfered edge

A shallow notch 1 as a tentative mark is engraved on a periphery of an ingot at a position corresponding to a predetermined crystal orientation in the step of grinding the periphery of the ingot. After the ingot is sliced to wafers, a mark 2 for indication of a crystal orientation is carved on a sliced wafer at a position determined on the basis of the notch 1 by laser marking. Thereafter, the wafer is chamfered to a round shape, and the notch 1 is removed by the chamfering. Since a part where the mark 2 shall be carved is determined on the basis of the notch 1, the mark 2 is efficiently carved on the wafer without the necessity of subjecting each wafer to an X-ray analyzer.

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Annaka, Japan

Keiichiro Asakawa