Breakage Ratio of Silicon Wafer during Fixed Diamond Wire Sawing

At a Glance

Metadata	Details
Publication Date	2022-11-02
Journal	Micromachines
Authors	Tengyun Liu, Yancai Su, Peiqi Ge
Institutions	Qilu University of Technology, Shandong University
Citations	6
Analysis	Full AI Review Included

Technical Documentation & Analysis: Wafer Breakage in Diamond Wire Sawing

This document analyzes the research concerning the mechanical stability and breakage ratio of monocrystalline silicon wafers during fixed diamond wire sawing (FDWS). As experts in MPCVD diamond materials, 6CCVD leverages this analysis to highlight the critical role of high-performance diamond in achieving the precision and stability required for ultra-thin wafer processing.

Executive Summary

Core Challenge Identified: The study systematically models and quantifies the relationship between wafer thickness, transverse vibration, maximum stress, and breakage ratio during fixed diamond wire sawing (FDWS).
Vibration as Primary Cause: Transverse vibration, induced by external excitation and wire movement, is confirmed as the main factor causing wafer breakage, with maximum amplitude reaching 160 µm for 0.2 mm thick wafers.
Quantified Breakage Risk: Wafer thinning significantly increases risk; reducing thickness from 0.2 mm to 0.15 mm increases the calculated breakage ratio from 2% to 6% in the completed sawing stage.
Modeling Accuracy: A theoretical model based on elastic thin plate theory and Weibull distribution was established and validated against Finite Element Method (FEM) simulations, showing a maximum relative error of 3.43%.
Material Stability Requirement: The research underscores the extreme mechanical demands placed on both the silicon wafer and the diamond tooling used in high-speed, high-precision machining processes.
6CCVD Value Proposition: 6CCVD specializes in producing high-modulus, ultra-hard Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) materials, essential for manufacturing the next generation of fixed diamond wire and high-stability machine components that minimize vibration and maximize yield in advanced slicing operations.

Technical Specifications

The following hard data points were extracted from the research paper, detailing the materials tested and the resulting mechanical performance metrics.

Parameter	Value	Unit	Context
Sawn Wafer Thickness (h)	0.2, 0.18, 0.15	mm	Tested monocrystalline silicon thicknesses
Wafer Length / Width (a, b/L)	156	mm	Standard wafer dimensions
Modulus of Elasticity (E)	165	GPa	Silicon material property
Poisson Ratio ($\mu$)	0.22	-	Silicon material property
Density ($\rho$)	2330	kg/m³	Silicon material property
Wire Diameter (d)	100	µm	Fixed diamond wire specification
Wire Speed ($v_s$)	2	m/s	Sawing parameter
Feed Rate ($v_f$)	6	µm/s	Sawing parameter
Excitation Frequency ($\omega_F$)	50	Hz	External vibration source
Weibull Scale Parameter ($\sigma_0$)	151.3	Mpa	Fracture strength parameter
Max Vibration Amplitude	160	µm	For 0.2 mm wafer at 156 mm cutting depth
Breakage Ratio (h=0.15 mm)	6	%	Calculated at completed sawing stage
Breakage Ratio (h=0.2 mm)	2	%	Calculated at completed sawing stage
Max Relative Error (Model vs. FEM)	3.43	%	Model validation accuracy

Key Methodologies

The study employed a rigorous theoretical and computational approach to analyze the mechanical behavior of the silicon wafers:

Theoretical Foundation: Established a mathematical model for calculating the breakage ratio based on the theory of elastic thin plates (Kirchhoff plate theory) and probabilistic fracture mechanics (Weibull distribution).
Vibration Modeling: Analyzed the free and forced vibration of the silicon wafer, treating it as an elastic cantilever plate with one fixed boundary (resin adhesive) and three free boundaries.
Boundary Conditions: Applied geometric boundary conditions for the fixed side and free boundary conditions involving partial derivatives of displacement for the free sides.
Force Simplification: Simplified the complex cutting force generated by diamond abrasives into a harmonic force excitation ($P(t) = F \sin \omega_F t$) for steady-state analysis.
Stress Determination: Calculated the maximum principal stress ($\sigma_{max}$) resulting from the transverse vibration, which was then used as the input for the Weibull distribution model to determine the break probability $P(\sigma)$.
Model Verification: Natural frequencies calculated by the theoretical model were compared against results from Finite Element Method (FEM) simulations to ensure model accuracy, confirming the approach for predicting dynamic response.
Parameter Variation: Systematically varied the cutting depth (0 to 156 mm) and wafer thickness (0.2 mm, 0.18 mm, 0.15 mm) to map the resulting changes in vibration amplitude, maximum stress, and final breakage ratio.

6CCVD Solutions & Capabilities

This research demonstrates that minimizing vibration and maximizing material stability are paramount for increasing yield in ultra-thin wafer manufacturing. 6CCVD’s expertise in high-quality MPCVD diamond materials directly supports the development of superior tooling and substrates required for these high-precision applications.

Applicable Materials for High-Precision Machining & Substrates

Application Requirement	Recommended 6CCVD Material	Key Benefit
High-Stability Tooling Components	High-Modulus PCD (Polycrystalline Diamond):	Extreme hardness and stiffness (E > 1000 GPa) to resist wear and minimize tool vibration, directly addressing the core cause of wafer breakage identified in the paper.
Precision Wire Drawing Dies	Optical Grade SCD (Single Crystal Diamond):	Highest purity and structural integrity for manufacturing ultra-precise dies required for drawing fixed diamond wire (e.g., 100 µm diameter) with minimal surface defects.
Advanced Heat Spreading/Substrates	SCD Substrates (Thermal Grade):	If the resulting silicon wafers are used in high-power PV or electronic devices, SCD offers thermal conductivity up to 2000 W/mK, ensuring device stability under operational stress.
Electrochemical/Sensor Applications	BDD (Boron-Doped Diamond):	For research extending into electrochemical processing of silicon or advanced sensor integration, BDD offers stable, conductive, and chemically inert surfaces.

Customization Potential for Research Replication and Extension

6CCVD provides comprehensive customization services necessary to replicate or extend the high-precision requirements of this research:

Custom Dimensions: We offer PCD plates/wafers up to 125 mm in diameter, allowing researchers to source large-area diamond components for advanced tooling or substrate testing.
Precision Thickness Control: We supply SCD and PCD materials with thickness control ranging from 0.1 µm up to 500 µm, enabling precise mechanical modeling and testing of ultra-thin structures.
Ultra-Low Roughness Polishing: Our internal polishing capabilities achieve surface roughness of Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD, crucial for minimizing friction and vibration in contact applications like wire sawing guides or machine components.
Integrated Metalization: For post-processing or device integration, 6CCVD offers in-house metalization services including Au, Pt, Pd, Ti, W, and Cu, essential for creating robust electrical contacts or bonding layers on diamond materials.

Engineering Support

6CCVD’s in-house PhD team specializes in the mechanical, thermal, and electronic properties of CVD diamond. We can assist engineers and scientists with material selection and specification for similar high-precision machining, PV, or high-stress mechanical projects, ensuring optimal material performance to maximize yield and stability.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Monocrystalline silicon is an important material for processing electronic and photovoltaic devices. The fixed diamond wire sawing technology is the first key technology for monocrystalline silicon wafer processing. A systematic study of the relationship between the fracture strength, stress and breakage rate is the basis for thinning silicon wafers. The external vibration excitation of sawing machine and diamond wire lead to the transverse vibration and longitudinal vibration for silicon wafers. The transverse vibration is the main reason of wafer breakage. In this paper, a mathematical model for calculating breakage ratio of silicon wafer is established. The maximum stress and breakage ratio for as-sawn silicon wafers are studied. It is found that the maximum amplitude of the silicon wafers with the size of 156 mm × 156 mm × 0.2 mm was 160 μm during the diamond wire sawing process. The amplitude, maximum stress and breakage rate of the wafers increased with the increase of the cutting depth. The smaller the silicon wafer thickness, the larger of silicon wafer breakage ratio. In the sawing stage, the breakage ratio of the 156 mm × 156 mm section with a thickness of 0.15 mm of silicon wafers is 6%.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi13111895

References

2016 - Surface chemical-bonds analysis of silicon particles from diamond-wire cutting of crystalline silicon [Crossref]
2016 - Wire sawing technology: A state-of-the-art review [Crossref]
2021 - Fabrication of thin resin-bonded diamond wire and its application to ductile mode wire sawing of mono-crystalline silicon [Crossref]
2016 - A cost roadmap for silicon heterojunction solar cells [Crossref]
2018 - Silicon foil solar cells on low cost supports [Crossref]
2018 - Review of status developments of high-efficiency crystalline silicon solar cells [Crossref]
2022 - Status and perspectives of crystalline silicon photovoltaics in research and industry [Crossref]