Method for slicing wafers from a workpiece
View Patent ↗A method for slicing wafers from a workpiece includes providing wire guide rolls that each have a grooved coating with a specific thickness, providing a fixed bearing respectively associated with each wire guide roll and providing a sawing wire including wire sections disposed in a parallel fashion. The wire sections are tensioned between the wire guide rolls and are moved relative to the workpiece so as to perform a sawing operation. The wire guide rolls cooled and the fixed bearings are cooled independently of the wire guide rolls.
1. A method for slicing wafers from a workpiece, the method comprising:
providing a workpiece;
providing a wire guide roll having a grooved coating with a specific thickness;
providing a fixed bearing respectively associated with the wire guide roll;
providing a sawing wire including wire sections disposed in a parallel fashion on the wire guide roll;
moving the wire sections of the sawing wire relative to the workpiece so as to perform a sawing operation;
cooling the wire guide roll using a channel at least partially disposed inside the wire guide roll; and
cooling the fixed bearing independently of the wire guide roll;
measuring an axial change in a length of the grooved coating of the wire guide roll during the sawing operation so as to provide a measurement;
generating a first and a second regulation signal based on the measurement; and
regulating the cooling of the wire guide roll using the first regulation signal and regulating the cooling of the fixed bearing using the second regulation signal.
2. The method recited in claim 1 , wherein the cooling the wire guide roll and the cooling the fixed bearing is carried out so as to maintain a difference ΔL W (x)−(ΔL F +ΔL B (x)) of less than 20 μm at every point in time during the sawing operation, wherein:
ΔL W (x) is an axial displacement of an axial position x on the workpiece due to a change in length of the workpiece as a result of a change in temperature of the workpiece,
ΔL F is a change in length of the fixed bearing as a result of a change in temperature of the fixed bearing, and
ΔL B (x) is an axial displacement of the axial position x on a coating of the wire guide roll due to a change in length of the coating as a result of a change in temperature of the coating.
3. The method recited in claim 2 , further comprising reacting to an axial displacement ΔL W (x) of greater than 0 μm by cooling the wire guide roll and the fixed bearing so as to realize the difference ΔL W (x)−(ΔL F +ΔL B (x)) that is less than 20 μm.
4. The method recited in claim 1 , further comprising:
providing a first predefinition curve that describes at least one of a temperature and a speed of a coolant for cooling the wire guide roll during the sawing operation;
providing a second predefinition curve that describes at least one of a temperature and a speed of a coolant for cooling the fixed bearing during the sawing operation;
cooling the wire guide roll in accordance with the first predefinition curve; and
cooling the fixed bearing in accordance with the second predefinition curve.
5. The method recited in claim 4 , wherein the first predefinition curve is a function of the thickness of the coating of the wire guide rolls.
6. The method recited in claim 2 , further comprising cooling the workpiece so as to maintain ΔL W (x) at less than 5 μm during the sawing operation, and wherein the cooling the wire guide roll and the cooling the fixed bearing is carried out so as to maintain a sum (ΔL F +ΔL B (x)) at less than 25 μm during the sawing operation.
7. The method recited in claim 1 , further comprising clamping the coating onto an underlying core of the wire guide roll.
8. The method recited in claim 1 , wherein the moving the wire sections of the saw wire relative to the workpiece is carried out in the presence of a sawing slurry.