Free abrasive diamond wire saw machining is often used to cut hard and brittle materials, especially for wafers in the semiconductor and optoelectronics industries. Wire saws, both free and fixed abrasive, have excellent flexibility, as compared to inner circular saws, outer saws, and ribbon saws, as they produce a narrower kerf, lower cutting forces, and less material waste. However, fixed abrasive wire saw machining is being considered more and more due to its potential for increased productivity and the fact that it is more environmentally friendly as it does not use special coolants that must be carefully disposed. The cutting forces generated during the wire saw process strongly affect the quality of the produced parts. However, the relationship between these forces and the process parameters has only been explored qualitatively. Based on analyzing the forces generated from the chip formation and friction of a single abrasive, this study derives an analytical cutting force model for the wire saw machining process. The analytical model explains qualitative observations seen in the literature describing the relationship between the cutting forces and the wafer feed rate, wire velocity, and contact length between the wire and wafer. Extensive experimental work is conducted to validate the analytical force model. Silicon carbide (SiC) monocrystal, which is employed extensively in the fields of microelectronics and optoelectronics and is known to be particularly challenging to process due to its extremely high hardness and brittleness, is used as the material in these experimental studies. The results show that the analytical force model can predict the cutting forces when wire saw machining SiC monocrystal wafers with average errors between the experimental and predicted normal and tangential forces of 9.98% and 12.1%, respectively.

Hard and brittle materials such as monocrystalline silicon still occupy an important position in the semiconductor industry, but hard and brittle materials are difficult to process because of their physical properties. Fixed-diamond abrasive wire-saw cutting is the most widely used method for slicing hard and brittle materials. The diamond abrasive particles on the wire saw wear to a certain extent, which affects the cutting force and wafer surface quality in the cutting process. In this experiment, keeping all the given parameters unchanged, a square silicon ingot is cut repeatedly with a consolidated diamond abrasive wire saw until the wire saw breaks. The experimental results show that the cutting force decreases with the increase in cutting times in the stable grinding stage. The wear of abrasive particles starts at the edges and corners, and the macro failure mode of the wire saw is fatigue fracture. The fluctuation of the wafer surface profile gradually decreases. The surface roughness of wafer is steady during the wear steady stage, and the large damage pits on the wafer surface are reduced in the whole process of cutting.

Monocrystalline silicon is widely used in the semiconductor market, but its hard and brittle physical properties make processing difficult. Fixed-diamond abrasive wire-saw (FAW) cutting is currently the most commonly used cutting method for hard and brittle materials due to advantages such as narrow cutting seams, low pollution, low cutting force and simple cutting process. During the process of cutting a wafer, the contact between the part and the wire is curved, and the arc length changes during the cutting process. This paper establishes a model of contact arc length by analyzing the cutting system. At the same time, a model of the random distribution of abrasive particles is established to solve the cutting force during the cutting process, using iterative algorithms to calculate cutting forces and chip surface saw marks. The error between the experiment and simulation of the average cutting force in the stable stage is less than 6%, and the errors with respect to the central angle and curvature of the saw arc on the wafer surface are less than 5% between the experiment and simulation. The relationship between the bow angle, contact arc length and cutting parameters is studied using simulations. The results show that the variation trend of the bow angle and contact arc length is consistent, increasing with an increase in the part feed rate and decreasing with an increase in the wire velocity.

Single crystal silicon wafers are often used as substrate material for integrated circuits. Often the wafer is cut by a wire with fixed abrasive diamond owning to a narrow kerf and a low cutting force. The cutting force changes during the process as the direction of wire movement continuously reverses (i.e., reciprocates), which may cause the wire saw to break, the wafer to collapse, and the wafer surface roughness to decrease even if the wire saw tension and the contact length between the wire and the wafer are fixed. In this work, a cutting force model including both normal and tangential forces was established to determine the relationship between the normal and tangential forces and the commanded wire speed. Separate controllers were developed to regulate both the normal force and the tangential force by adjusting the wire velocity. Experimental studies were conducted for wire saw processing of single crystal silicon wafers. Compared with a process using constant wire velocity, regulating the normal force can significantly reduce the processing time and the wafer surface roughness. The average improvements in processing time and wafer surface roughness are approximately 11% and 56%, respectively, when using normal force control, and approximately 29% and 30%, respectively, when using tangential force control. The results show that the normal and tangential forces can be well regulated during the machining process. In addition, the wafer surface roughness and machining time were lower in both experiments where the forces were regulated than in the experiment where a constant wire velocity was used. This paper demonstrates that the novel concept of regulating process forces in wire saw machining by adjusting the wire velocity can be used to optimize the cutting process of single crystal silicon, making the process more productive while decreasing the part roughness.

Fixed-diamond abrasive wire saw cutting is one of the most common methods for cutting hard and brittle materials. This process has unique advantages including a narrow kerf and the ability to use a relatively small cutting force. In the cutting process, controlling the main process parameters can improve the processing efficiency, obtaining a better processing surface roughness. This work designs the PI controller (Proportional–Integral controller) based on the reciprocating wire saw cutting process. The control objects are the workpiece feed rate and wire saw velocity, and the control objective is the normal cutting force. For the control trials, several reference values of various normal cutting forces were chosen. The effects of feed rate and saw velocity on the cutting surface finish and cutting time were investigated in this work using wire saw cutting analysis on a square monocrystalline silicon specimen. The results of this study showed that under a constant applied force of 2.5 N, the optimal feed rate of the diamond wire through the specimen could reduce cutting time by 42% while achieving a 60% improvement in the measured surface finish. Likewise, optimal control of the wire saw velocity could reduce cycle time by 18% with a 45% improvement in the surface finish. Consequently, the feed speed control is more effective than the wire saw velocity.