Experimental Study on the Influence of Wire-Saw Wear on Cutting Force and Silicon Wafer Surface

At a Glance

Metadata	Details
Publication Date	2023-05-09
Journal	Materials
Authors	Lie Liang, Shujuan Li, Kehao Lan, Ruijiang Yu, Jiabin Wang
Institutions	Xi’an University of Technology
Citations	14
Analysis	Full AI Review Included

Executive Summary

This study experimentally investigates the critical relationship between fixed-diamond wire-saw wear, cutting force dynamics, and resulting monocrystalline silicon (Si) wafer surface quality during repeated slicing operations.

Wear-Force Correlation: The normal cutting force (F_n) exhibits a gradual decrease during the stable wear stage (wafers 2-9). This reduction is attributed to the flattening and rounding of abrasive particles, which decreases the wire bow angle and the resulting force component.
Abrasive Wear Mechanism: Diamond abrasive wear initiates at the edges and corners, progressing to particle flattening. This flattening reduces the depth of penetration and shifts material removal from brittle fracture (large pits) toward plastic removal.
Wafer Surface Improvement: The amplitude of the wafer surface profile (peak-to-trough distance) steadily decreases during the stable wear stage, indicating improved surface uniformity as the abrasives flatten.
Damage Reduction: Large damage pits, characteristic of brittle material removal by sharp, new abrasives, are significantly reduced in number and size as the wire saw wears, leading to a more uniform surface topography.
Failure Mode: The macro failure mode of the wire saw was identified as fatigue fracture, occurring in the middle of the processing area, suggesting that the quality of the wire matrix (not just abrasive wear) limits the saw’s lifespan.
Process Control Insight: The observed fluctuations in cutting force and subsequent increases in surface roughness in the later stages (wafers 10-15) correlate directly with the shedding and damage of abrasive particles, providing a potential real-time indicator for end-of-life processing.

Technical Specifications

Parameter	Value	Unit	Context
Part Material	Silicon monocrystal	N/A	Ingot being sliced
Ingot Dimensions	36 x 23 x 200	mm	Rectangular ingot size
Cutting Surface Area	36 x 23	mm²	Wire-part contact area
Part Feed Rate (V_x)	0.75	mm/min	Constant experimental parameter
Wire Saw Velocity (V_s)	1	m/s	Constant experimental parameter
Abrasive Type	JR2-type diamond	N/A	Fixed abrasive on nickel matrix
Abrasive Grain Size	50-60	µm	Average particle size
Total Wafers Cut	15	N/A	Until wire saw fatigue fracture
Dynamometer Model	ATI FT19500	N/A	Force measurement device
Dynamometer Range (Z-axis)	±100	N	Normal cutting force measurement
Surface Roughness (R_a) Range	0.55 to 0.65	µm	Measured across 15 wafers
Stable Wear Stage	Wafers 3 to 9	N/A	Period of stable R_a and decreasing F_n

Key Methodologies

The experiment utilized a small-sized cutting machine to repeatedly slice a square monocrystalline silicon ingot until the consolidated diamond abrasive wire saw broke, ensuring abrasive wear was the primary variable affecting results.

Slicing Setup: A fixed-diamond abrasive wire saw (50-60 µm diamond grains in a nickel matrix) was tensioned on the machine. A rectangular Si ingot (36 mm x 23 mm) was used to maintain a constant contact length during the stable cutting phase.
Process Parameters: Wire saw velocity (V_s) was set at 1 m/s, and the part feed rate (V_x) was fixed at 0.75 mm/min. These parameters remained constant throughout the cutting of all 15 wafers.
Real-Time Force Measurement: Normal cutting force (F_n) was collected in real-time using an ATI FT19500 dynamometer consolidated with the part fixture.
Wire Wear Tracking (In-Situ): After cutting each wafer, the wire surface was photographed at six equidistant positions between the idler pulleys using a digital microscope (Anyty 3R-MSUSB601) to track abrasive particle wear morphology.
Wire Failure Analysis (Ex-Situ): After the wire broke, the fracture port and worn abrasive surfaces were analyzed using Scanning Electron Microscopy (SEM, Merlin Compact) to determine the macro failure mode and detailed wear characteristics.
Wafer Surface Quality Assessment:
- Profile and Roughness: Wafer surface roughness (R_a) and surface profile were measured using a Leica DCM3D white light confocal interference microscope. Measurements were taken in the stable cutting region (25 mm to 30 mm along the cut direction).
- Topography: Wafer surface scratches and damage pits were observed using SEM (Merlin Compact) at 200x and 500x magnification.

Commercial Applications

The findings provide critical data for optimizing the fixed-diamond wire sawing process, particularly in high-volume manufacturing environments where tool wear significantly impacts cost and quality.

Semiconductor Wafer Manufacturing: Directly applicable to the primary slicing process of Si ingots, enabling tighter control over wafer thickness variation and surface integrity, crucial for subsequent device fabrication steps.
Photovoltaic (PV) Industry: Relevant for high-efficiency solar cell production, where minimizing kerf loss and improving surface quality (reducing subsurface damage) directly lowers overall manufacturing costs.
Process Monitoring and Control: The established correlation between cutting force fluctuations and abrasive particle shedding allows for the development of dynamic process control models. These models can predict the optimal time for wire replacement or adjust parameters based on real-time force data.
Wafer Screening and Classification: The ability to link abrasive wear state to specific surface characteristics (e.g., reduction of large brittle pits) allows manufacturers to screen and classify wafers based on their expected quality immediately after slicing, minimizing downstream processing failures.
Tool Design and Material Science: Provides feedback for improving the wire saw matrix material (nickel plating) to resist fatigue fracture and enhance the bonding strength of diamond particles, thereby extending tool life and improving stable wear duration.

View Original Abstract

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.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma16103619

References

2017 - Analytical Force Modeling of Fixed Abrasive Diamond Wire Saw Machining with Application to SiC Monocrystal Wafer Processing [Crossref]
2023 - Study on nanometer cutting mechanism of single crystal silicon at different temperatures [Crossref]
2020 - Experiment and theoretical prediction for surface roughness of PV polycrystalline silicon wafer in electroplated diamond wire sawing [Crossref]
2023 - Molecular dynamics simulation on crystal defects of single-crystal silicon during elliptical vibration cutting [Crossref]
2022 - Theoretical study on sawing force of ultrasonic vibration assisted diamond wire sawing (UAWS) based on abrasives wear [Crossref]
2020 - Characterization of electroplated diamond wires and the resulting workpiece quality in silicon sawing [Crossref]
2018 - Experimental investigation of tool wear in electroplated diamond wire sawing of silicon [Crossref]
2023 - Modeling and experimental investigation of monocrystalline silicon wafer cut by diamond wire saw [Crossref]
2022 - Experiment and theoretical prediction for subsurface microcracks and damage depth of multi-crystalline silicon wafer in diamond wire sawing [Crossref]